Granit nyaéta jenis batuan beku anu digali kusabab kakuatan, kapadetan, daya tahan, sareng résistansi anu ekstrim kana korosi. Tapi granit ogé serbaguna pisan - éta henteu ngan ukur pikeun pasagi sareng pasagi panjang! Kanyataanna, Kami percaya diri damel sareng komponén granit anu direkayasa dina bentuk, sudut, sareng kurva tina sagala variasi sacara rutin - kalayan hasil anu saé pisan.
Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:
■ tiasa diolah nganggo mesin
■ rata pisan nalika dipotong sareng réngsé
■ tahan karat
■ awét
■ awét
Komponen granit ogé gampang dibersihkeun. Nalika nyieun desain khusus, pastikeun milih granit pikeun kauntungan anu unggul.

STANDAR / APLIKASI KEGUNAAN LUHUR
Granit anu dianggo ku ZHHIMG pikeun produk pelat permukaan standar kami ngagaduhan kandungan kuarsa anu luhur, anu nyayogikeun résistansi anu langkung ageung kana karusakan sareng karusakan. Warna Hideung Superior kami ngagaduhan tingkat panyerepan cai anu handap, ngaminimalkeun kamungkinan alat ukur presisi anjeun karat nalika dipasang dina pelat. Warna granit anu ditawarkeun ku ZHHIMG ngahasilkeun kirang silau, anu hartosna kirang kacapean panon pikeun individu anu nganggo pelat. Kami parantos milih jinis granit kami bari mertimbangkeun ékspansi termal dina upaya pikeun ngajaga aspék ieu minimal.

CUSTOM APPLICATIONS
Nalika aplikasi anjeun meryogikeun pelat kalayan bentuk khusus, sisipan ulir, slot atanapi pamrosésan anu sanés, anjeun kedah milih bahan sapertos Hideung Jinan Hideung. Bahan alami ieu nawiskeun kaku anu unggul, peredam geter anu saé, sareng kamampuan pamrosésan anu ditingkatkeun.

Penting pikeun dicatet yén warna nyalira sanés indikasi kualitas fisik batu. Sacara umum, warna granit aya hubunganana langsung sareng ayana atanapi henteuna mineral, anu panginten henteu aya hubunganana sareng kualitas anu ngajantenkeun bahan pelat permukaan anu saé. Aya granit pink, kulawu, sareng hideung anu saé pisan pikeun pelat permukaan, ogé granit hideung, kulawu, sareng pink anu henteu cocog pisan pikeun aplikasi presisi. Ciri-ciri penting granit, sabab aya hubunganana sareng panggunaanana salaku bahan pelat permukaan, henteu aya hubunganana sareng warna, sareng sapertos kieu:
■ Kakakuan (defleksi dina beban - dituduhkeun ku Modulus Élastisitas)
■ Karasa
■ Kapadetan
■ Résistansi ngagem
■ Stabilitas
■ Porositas

Kami parantos nguji seueur bahan granit sareng ngabandingkeun bahan-bahan ieu. Tungtungna kami kéngingkeun hasilna, granit hideung Jinan mangrupikeun bahan pangsaéna anu kantos kami terang. Granit Hideung India sareng granit Afrika Kidul sami sareng Granit Hideung Jinan, tapi sipat fisikna kirang tibatan Granit Hideung Jinan. ZHHIMG bakal teras milarian langkung seueur bahan granit di dunya sareng ngabandingkeun sipat fisikna.

Kanggo ngobrol langkung seueur ngeunaan granit anu pas pikeun proyék anjeun, mangga ngahubungi kamiinfo@zhhimg.com.

Pabrik anu béda-béda nganggo standar anu béda-béda. Aya seueur standar di dunya.
Standar DIN, ASME B89.3.7-2013 atanapi Spésifikasi Féderal GGG-P-463c (Pelat Permukaan Granit) sareng saterasna salaku dasar pikeun spésifikasina.

Sareng kami tiasa ngadamel pelat inspeksi presisi granit numutkeun kabutuhan anjeun. Wilujeng sumping ngahubungi kami upami anjeun hoyong terang langkung seueur inpormasi ngeunaan langkung seueur standar.

Karataan bisa dianggap salaku sadaya titik dina beungeut anu aya dina dua bidang sajajar, bidang dasar sareng bidang hateup. Pangukuran jarak antara bidang nyaéta karataan sakabéh beungeut. Pangukuran karataan ieu umumna ngagaduhan toleransi sareng tiasa kalebet sebutan kelas.

Contona, toleransi kerataan pikeun tilu tingkatan standar dihartikeun dina spésifikasi féderal sakumaha anu ditangtukeun ku rumus ieu:
■ Kelas Laboratorium AA = (40 + diagonal kuadrat/25) x .000001" (unilateral)
■ Tingkat Inspeksi A = Tingkat Laboratorium AA x 2
■ Kelas Ruang Pakakas B = Kelas Laboratorium AA x 4.

Pikeun pelat permukaan ukuran standar, kami ngajamin toleransi kerataan anu ngaleuwihan sarat spésifikasi ieu. Salian ti kerataan, ASME B89.3.7-2013 & Spésifikasi Féderal GGG-P-463c ngabahas topik-topik kalebet: akurasi pangukuran ulang, sipat bahan granit pelat permukaan, hasil akhir permukaan, lokasi titik pangrojong, kaku, metode pamariksaan anu tiasa ditampi, pamasangan sisipan ulir, jsb.

Pelat permukaan granit ZHHIMG sareng pelat inspeksi granit nyumponan atanapi ngaleuwihan sadaya sarat anu ditetepkeun dina spésifikasi ieu. Ayeuna, teu aya spésifikasi anu pasti pikeun pelat sudut granit, paralel, atanapi pasagi induk.

Sareng anjeun tiasa mendakan rumus pikeun standar sanésna diUNDUH.

Mimitina, penting pikeun ngajaga piring tetep bersih. Lebu abrasif anu kasebar di udara biasana mangrupikeun sumber karusakan anu paling ageung dina piring, sabab condong nempel dina benda kerja sareng permukaan kontak alat ukur. Kadua, tutup piring anjeun pikeun ngajagaan tina lebu sareng karusakan. Umur pakai tiasa diperpanjang ku cara nutupan piring nalika henteu dianggo, ku cara muterkeun piring sacara périodik supados hiji daérah henteu kaleuleuwihi dianggo, sareng ku cara ngagentos bantalan kontak baja dina alat ukur ku bantalan karbida. Ogé, hindari neundeun tuangeun atanapi inuman lemes dina piring. Catet yén seueur inuman lemes ngandung asam karbonat atanapi fosfat, anu tiasa ngaleyurkeun mineral anu langkung lemes sareng ninggalkeun liang alit dina permukaan.

Ieu gumantung kana kumaha piring éta dianggo. Upami tiasa, kami nyarankeun pikeun ngabersihkeun piring di awal dinten (atanapi shift damel) sareng deui di akhirna. Upami piring janten kotor, khususna ku cairan anu berminyak atanapi lengket, éta kedah langsung dibersihkeun.

Bersihkeun pelat sacara rutin nganggo cairan atanapi pembersih pelat permukaan ZHHIMG Waterless. Pilihan larutan pembersih penting pisan. Upami pelarut anu gampang nguap dianggo (aseton, pengencer lak, alkohol, jsb.) penguapan bakal niiskeun permukaan, sareng ngabengkokkeunana. Dina hal ieu, perlu ngantepkeun pelat normal sateuacan dianggo atanapi kasalahan pangukuran bakal kajantenan.

Jumlah waktos anu diperyogikeun pikeun piring pikeun normal bakal bénten-bénten gumantung kana ukuran piring, sareng jumlah pendinginan. Sajam cekap pikeun piring anu langkung alit. Dua jam panginten diperyogikeun pikeun piring anu langkung ageung. Upami nganggo pembersih basis cai, ogé bakal aya sababaraha pendinginan anu nguap.

Pelat éta ogé bakal nahan cai, sareng ieu tiasa nyababkeun karat dina bagian logam anu kontak sareng permukaan. Sababaraha pembersih ogé bakal ninggalkeun sésa anu lengket saatos garing, anu bakal narik lebu anu ngalayang, sareng saleresna ningkatkeun karusakan, tinimbang ngiranganana.

Ieu gumantung kana panggunaan pelat sareng lingkunganana. Kami nyarankeun pelat atanapi asesoris granit presisi énggal nampi kalibrasi ulang lengkep dina sataun ti saprak pameseran. Upami pelat permukaan granit bakal sering dianggo, disarankeun pikeun ngirangan interval ieu janten genep bulan. Inspeksi bulanan pikeun kasalahan pangukuran anu diulang nganggo level Éléktronik, atanapi alat anu sami bakal nunjukkeun titik-titik anu ruksak sareng ngan ukur peryogi sababaraha menit kanggo dilaksanakeun. Saatos hasil kalibrasi ulang anu munggaran ditangtukeun, interval kalibrasi tiasa diperpanjang atanapi disingget sakumaha anu diidinan atanapi diwajibkeun ku sistem kualitas internal anjeun.

Kami tiasa nawiskeun jasa pikeun ngabantosan anjeun mariksa sareng ngalibrasi pelat permukaan granit anjeun.

Aya sababaraha kamungkinan sabab pikeun variasi antara kalibrasi:

• Beungeutna dikumbah ku larutan panas atanapi tiis sateuacan kalibrasi, sareng teu dibéré waktos anu cekap pikeun normalisasi.
• Pelatna teu dirojong kalawan bener
• Parobahan suhu
• Draf
• Sinar panonpoé langsung atanapi panas radiasi sanésna dina permukaan pelat. Pastikeun yén lampu di luhur henteu manaskeun permukaan
• Variasi dina gradien suhu vertikal antara usum tiris sareng usum panas (Upami tiasa, terang suhu gradien vertikal nalika kalibrasi dilaksanakeun.)
• Pelat teu dibéré waktos anu cekap pikeun normal deui saatos pangiriman
• Panggunaan alat pamariksaan anu teu leres atanapi panggunaan alat anu henteu dikalibrasi
• Parobahan permukaan akibat tina maké

Sabaraha jinis liang dina granit presisi?

Slot dina Komponen Granit Presisi

Pikeun seueur pabrik, rohangan pamariksaan sareng laboratorium, pelat permukaan granit presisi dianggo salaku dasar pikeun pangukuran anu akurat. Kusabab unggal pangukuran linier gumantung kana permukaan rujukan anu akurat tina mana diménsi ahir dicandak, pelat permukaan nyayogikeun bidang rujukan anu pangsaéna pikeun pamariksaan sareng tata letak padamelan sateuacan dimesin. Éta ogé mangrupikeun dasar anu idéal pikeun ngadamel pangukuran jangkungna sareng permukaan gaging. Salajengna, tingkat kerataan, stabilitas, kualitas sakabéhna sareng padamelan anu luhur ngajantenkeun éta pilihan anu saé pikeun masang sistem gaging mékanis, éléktronik sareng optik anu canggih. Pikeun prosés pangukuran ieu, penting pikeun ngajaga pelat permukaan dikalibrasi.

Repeat Measurements and Flatness

Pangukuran rata jeung pangulangan duanana penting pisan pikeun mastikeun permukaan anu presisi. Rata bisa dianggap salaku sadaya titik dina permukaan anu aya dina dua bidang sajajar, bidang dasar jeung bidang hateup. Pangukuran jarak antara bidang nyaéta rata sakabéh permukaan. Pangukuran rata ieu umumna mibanda toleransi jeung bisa ngawengku sebutan kelas.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:

Standar DIN, Standar GB, Standar ASME, standar JJS... nagara anu béda-béda kalayan pendirian anu béda-béda...

Langkung seueur rinci ngeunaan standar.

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

Pikeun mastikeun pelat permukaan nyumponan spésifikasi pangukuran rata sareng pangukuran anu diulang, produsén pelat permukaan granit kedah nganggo Spésifikasi Federal GGG-P-463c salaku dasar pikeun spésifikasina. Standar ieu ngabahas akurasi pangukuran anu diulang, sipat bahan granit pelat permukaan, hasil akhir permukaan, lokasi titik pangrojong, kaku, metode pamariksaan anu tiasa ditampi sareng pamasangan sisipan anu diulir.

Checking Plate Accuracy

Ku nuturkeun sababaraha pedoman saderhana, investasi dina pelat permukaan granit kedah tahan salami mangtaun-taun. Gumantung kana panggunaan pelat, lingkungan bengkel sareng akurasi anu diperyogikeun, frékuénsi mariksa akurasi pelat permukaan béda-béda. Aturan umum nyaéta pelat énggal kedah nampi kalibrasi ulang lengkep dina sataun saatos pameseran. Upami pelat sering dianggo, disarankeun pikeun ngirangan interval ieu janten genep bulan.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations

Dina sababaraha kasus, aya variasi antara kalibrasi pelat permukaan. Kadang-kadang faktor sapertos parobahan permukaan anu disababkeun ku karusakan, panggunaan alat pamariksaan anu salah atanapi panggunaan alat anu henteu dikalibrasi tiasa nyababkeun variasi ieu. Nanging, dua faktor anu paling umum nyaéta suhu sareng pangrojong.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Extend Plate Life

Nuturkeun sababaraha pedoman bakal ngirangan karusakan dina pelat permukaan granit sareng pamustunganana, manjangkeun umurna.

Mimitina, penting pikeun ngajaga pelat tetep bersih. Lebu abrasif anu ngalayang di udara biasana mangrupikeun sumber karusakan sareng cimata anu paling ageung dina pelat, sabab condong nempel dina benda kerja sareng permukaan kontak alat ukur.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Puterkeun pelat sacara périodik supados hiji daérah henteu dianggo kaleuleuwihi. Ogé, disarankeun pikeun ngagentos bantalan kontak baja dina gauging ku bantalan karbida.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap

Nalika pelat permukaan granit peryogi diropéa, pertimbangkeun naha jasa ieu kedah dilaksanakeun di tempat atanapi di fasilitas kalibrasi. Langkung saé upami pelat dipasang deui di pabrik atanapi fasilitas khusus. Nanging, upami pelatna henteu ruksak parah, umumna dina 0,001 inci tina toleransi anu diperyogikeun, éta tiasa diropéa di tempat. Upami pelat ruksak dugi ka langkung ti 0,001 inci tina toleransi, atanapi upami aya liang atanapi sobekan anu parah, maka éta kedah dikirim ka pabrik pikeun digiling sateuacan dipasang deui.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Kudu ati-ati pisan dina milih teknisi kalibrasi sareng resurfacing di tempat. Nyuhunkeun akreditasi sareng verifikasi alat anu bakal dianggo ku teknisi gaduh kalibrasi anu tiasa dilacak. Pangalaman ogé mangrupikeun faktor anu penting, sabab peryogi mangtaun-taun pikeun diajar kumaha cara ngalapis granit presisi kalayan leres.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.Q

Checklist for Calibration Variations

1. Beungeutna dikumbah ku larutan panas atanapi tiis sateuacan kalibrasi sareng teu dibéré waktos anu cekap pikeun normalisasi.

2. Pelatna teu ditopang kalawan bener.

3. Parobahan suhu.

4. Draf.

5. Sinar panonpoé langsung atanapi panas radiasi sanésna dina permukaan pelat. Pastikeun yén lampu di luhur henteu manaskeun permukaan.

6. Variasi dina gradien suhu vertikal antara usum tiris sareng usum panas. Upami tiasa, terang suhu gradien vertikal nalika kalibrasi dilaksanakeun.

7. Pelat teu dibéré waktos anu cekap pikeun normal deui saatos dikirim.

8. Panggunaan alat pamariksaan anu teu leres atanapi panggunaan alat anu teu dikalibrasi.

9. Parobahan beungeut akibat tina maké.

Tech Tips

• Kusabab unggal pangukuran linier gumantung kana permukaan rujukan anu akurat tina mana diménsi ahir dicandak, pelat permukaan nyayogikeun bidang rujukan anu pangsaéna pikeun pamariksaan padamelan sareng tata letak sateuacan dimesin.
• Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.
• Program pamariksaan anu efektif kedah ngawengku pamariksaan rutin nganggo autokolimator, anu nyayogikeun kalibrasi anu saleresna tina kerataan sakabéhna anu tiasa dilacak ka Otoritas Inspeksi Nasional.

Di antara partikel mineral anu ngawangun granit, langkung ti 90% nyaéta feldspar sareng kuarsa, anu paling seueur nyaéta feldspar. Feldspar sering bodas, kulawu, sareng beureum daging, sareng kuarsa biasana teu warnaan atanapi bodas kulawu, anu ngawangun warna dasar granit. Feldspar sareng kuarsa mangrupikeun mineral anu teuas, sareng hésé dipindahkeun ku péso baja. Sedengkeun pikeun bintik poék dina granit, utamina mika hideung, aya sababaraha mineral sanés. Sanaos biotit relatif lemes, kamampuanna pikeun nolak setrés henteu lemah, sareng dina waktos anu sami aranjeunna gaduh jumlah sakedik dina granit, sering kirang ti 10%. Ieu mangrupikeun kaayaan bahan dimana granit khususna kuat.

Alesan séjén kunaon granit téh kuat nyaéta partikel mineralna silih kabeungkeut pageuh sarta silih tempelkeun. Pori-porina mindeng kurang ti 1% tina total volume batu. Ieu méré granit kamampuh pikeun nahan tekanan anu kuat sarta henteu gampang ditembus ku kalembaban.

Komponen granit didamel tina batu anu henteu tahan karat, asam sareng alkali, tahan aus anu saé sareng umur panjang, henteu aya perawatan khusus. Komponen presisi granit biasana dianggo dina perkakas industri mesin. Ku alatan éta, aranjeunna disebut komponén presisi granit atanapi komponén granit. Ciri-ciri komponén presisi granit dasarna sami sareng platform granit. Bubuka kana perkakas sareng pangukuran komponén presisi granit: Mesin presisi sareng téknologi mesin mikro mangrupikeun arah pamekaran anu penting pikeun industri manufaktur mesin, sareng éta parantos janten indikator penting pikeun ngukur tingkat téknologi tinggi. Kamekaran téknologi canggih sareng industri pertahanan henteu tiasa dipisahkeun tina mesin presisi sareng téknologi mesin mikro. Komponen granit tiasa digeser kalayan lancar dina pangukuran, tanpa stagnasi. Pangukuran permukaan kerja, goresan umum henteu mangaruhan akurasi pangukuran. Komponen granit kedah dirancang sareng diproduksi numutkeun sarat sisi paménta.

Widang aplikasi:

Sapertos anu urang terang, beuki seueur mesin sareng peralatan anu milih komponén granit presisi.

Komponen granit dianggo pikeun gerakan dinamis, motor linier, cmm, cnc, mesin laser...

wilujeng sumping ngahubungi kami kanggo inpormasi lengkep.

Alat ukur granit sareng komponén mékanis granit didamel tina granit Hideung Jinan anu kualitasna luhur. Kusabab presisi anu luhur, awét, stabilitas anu saé sareng tahan korosi, alat-alat ieu beuki seueur dianggo dina pamariksaan produk industri modéren sareng widang ilmiah sapertos aerospace mékanis sareng panalungtikan ilmiah.

Kauntungan

----Dua kali leuwih teuas tibatan beusi cor;

----Parobahan minimal dina diménsi disababkeun ku parobahan suhu;

----Bebas tina remuk, janten teu aya gangguan padamelan;

----Bebas tina gerinda atanapi tonjolan kusabab struktur butir anu lemes sareng teu lengket anu signifikan, anu mastikeun tingkat kerataan anu luhur salami umur panjang sareng henteu nyababkeun karusakan kana bagian atanapi instrumen sanés;

---- Operasi anu bébas masalah pikeun dianggo sareng bahan magnét;

---- Umur panjang sareng bébas karat, anu ngahasilkeun biaya perawatan anu handap.

Pelat permukaan granit anu presisi ieu dilapis sacara presisi kana standar kerataan anu luhur pikeun ngahontal akurasi sareng dianggo salaku dasar pikeun masang sistem pangukur mékanis, éléktronik, sareng optik anu canggih.

Sababaraha fitur unik tina pelat permukaan granit:

Kasaragaman dina Karasa;

Akurat dina Kaayaan beban;

Nyerep Geter;

Gampang dibersihkeun;

Tahan Bungkus;

Porositas Handap;

Henteu Ngagosok;

Non-Magnétik

Kaunggulan Pelat Permukaan Granit

First, the rock after a long period of natural aging, uniform structure, coefficient minimum, the internal stress completely disappear, not deformed, so the precision is high.

Kirim Surélék

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Precision Granite Base Can Improve Machine Tool Performances

Requirements are constantly increasing in mechanical engineering in general and in machine tool construction in particular. Achieving maximum precision and performance values without increasing costs are constant challenges to being competitive. The machine tool bed is a decisive factor here. Therefore, more and more machine tool manufacturers are relying on granite. Due to its physical parameters, it offers clear advantages that cannot be achieved with steel or polymer concrete.

Granite is a so-called volcanic deep rock and has a very dense and homogeneous structure with an extremely low coefficient of expansion, low thermal conductivity and high vibration damping.

Below you will discover why the common opinion that granite is mainly only suitable as machine base for high-end coordinate measuring machines is long outdated and why this natural material as a machine tool base is a very advantageous alternative to steel or cast iron even for high-precision machine tools.

We can manufacture granite components for dynamic motion, granite components for linear motors, granite components for ndt, granite components for xray, granite components for cmm, granite components for cnc, granite precision for laser, granite components for aerospace, granite components for precision stages...

High Added Value Without Additional Costs
The increasing use of granite in mechanical engineering is not so much due to the massive increase in the price of steel. Rather, it is because the added value for the machine tool achieved with a machine bed made of granite is possible at very little or no extra cost. This is proven by cost comparisons of well-known machine tool manufacturers in Germany and Europe.

The considerable gain in thermodynamic stability, vibration damping and long-term precision made possible by granite cannot be achieved with a cast iron or steel bed, or only at relatively high cost. For example, thermal errors can account for up to 75% of the total error of a machine, with compensation often attempted for by software – with moderate success. Due to its low thermal conductivity, granite is the better foundation for long-term precision.

With a tolerance of 1 μm, granite easily meets the flatness requirements according to DIN 876 for the degree of accuracy 00. With a value of 6 on the hardness scale 1 to 10, it is extremely hard, and with its specific weight of 2.8g/cm³ it almost reaches the value of aluminium. This also results in additional advantages such as higher feed rates, higher axis accelerations and an extension of the tool life for cutting machine tools. Thus, the change from a cast bed to a granite machine bed moves the machine tool in question into the high-end class in terms of precision and performance – at no extra cost.

Granite’s Improved Ecological Footprint
In contrast to materials such as steel or cast iron, natural stone does not have to be produced with a great deal of energy and using additives. Only relatively small amounts of energy are required for quarrying and surface treatment. This results in a superior ecological footprint, which even at the end of a machine’s life surpasses that of steel as a material. The granite bed can be the basis for a new machine or be used for completely different purposes such as shredding for road construction.

Nor are there any shortages of resources for granite. It is a deep rock formed from magma within the earth’s crust. It has ‘matured’ for millions of years and is available in very large quantities as a natural resource on almost all continents, including all of Europe.

Conclusion: The numerous demonstrable advantages of granite compared to steel or cast iron justify the increasing willingness of mechanical engineers to use this natural material as a foundation for high-precision, high-performance machine tools. Detailed information about granite properties, which are advantageous for machine tools and mechanical engineering, can be found in this further article.

A repeat measurement is a measurement of local flatness areas. The Repeat Measurement specification states that a measurement taken anywhere on the surface of a plate will repeat within the stated tolerance. Controlling local area flatness tighter than overall flatness guarantees a gradual change in surface flatness profile thereby minimizing local errors.

Most manufacturers, including imported brands, adhere to the Federal Specification of overall flatness tolerances but many overlook the repeat measurements. Many of the low value or budget plates available in the market today will not guarantee repeat measurements. A manufacturer who does not guarantee repeat measurements is NOT producing plates that meet the requirements of ASME B89.3.7-2013 or Federal Specification GGG-P-463c, or DIN 876, GB, JJS...

Both are critical to ensure a precision surface for accurate measurements. Flatness specification alone is not sufficient to guarantee measurement accuracy. Take as an example, a 36 X 48 Inspection Grade A surface plate, which meets ONLY the flatness specification of .000300". If the piece being checked bridges several peaks, and the gage being used is in a low spot, the measurement error could be the full tolerance in one area, 000300"! Actually, it can be much higher if the gage is resting on the slope of an incline.

Errors of .000600"-.000800" are possible, depending upon the severity of the slope, and the arm length of the gage being used. If this plate had a Repeat Measurement specification of .000050"F.I.R. then the measurement error would be less than .000050" regardless of where the measurement is taken on the plate. Another problem, which usually arises when an untrained technician attempts to resurface a plate on-site, is the use of Repeat Measurements alone to certify a plate.

The instruments that are used to verify repeatability are NOT designed to check overall flatness. When set to zero on a perfectly curved surface, they will continue to read zero, whether that surface is perfectly flat or perfectly concave or convex 1/2"! They simply verify the uniformity of the surface, not the flatness. Only a plate that meets both the flatness specification AND the repeat measurement specification truly meets the requirements of ASME B89.3.7-2013  or Federal Specification GGG-P-463c.

Ask us about or flatness specification and repeat measurement promise by calling +86 19969991659 or emailing INFO@ZHHIMG.COM

Yes, but they can only be guaranteed for a specific vertical temperature gradient. The effects of thermal expansion on the plate could easily cause a change in accuracy greater than the tolerance if there is a change in the gradient. In some cases, if the tolerance is tight enough, the heat absorbed from overhead lighting can cause enough of a gradient change over several hours.

Granite has a coefficient of thermal expansion of approximately .0000035 inches per inch per 1°F. As an example: A 36" x 48" x 8" surface plate has an accuracy of .000075" (1/2 of Grade AA) at a gradient of 0°F, the top and bottom are the same temperature. If the top of the plate warms up to the point where it is 1°F warmer than the bottom, the accuracy would change to .000275" convex ! Therefore, ordering a plate with a tolerance tighter than Laboratory Grade AA should only be considered if there is adequate climate control.

A surface plate should be supported at 3 points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered. Only 3 points can rest solidly on anything but a precision surface.

The plate should be supported at these points during production, and it should be supported only at these three points while in use. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same 3 points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. All zhhimg steel stands have support beams designed to line up with the proper support points.

If the plate is properly supported, precise leveling is only necessary if your application calls for it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

Why Choose Granite for Machine Bases and Metrology Components?

The answer is 'yes' for almost every application. The advantages of granite include: No rust or corrosion, almost immune to warping, no compensating hump when nicked, longer wear life, smoother action, greater precision, virtually non-magnetic, low co-efficient of thermal expansion, and low maintenance cost.

Granite is a type of igneous rock quarried for its extreme strength, density, durability, and resistance to corrosion. But granite is also very versatile– it’s not just for squares and rectangles! In fact, Starrett Tru-Stone confidently works with granite components engineered in shapes, angles, and curves of all variations on a regular basis—with excellent outcomes.

Through our state of the art processing, cut surfaces can be exceptionally flat. These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components. Granite is:

machineable
precisely flat when cut and finished
rust resistant
durable
long lasting
Granite components are also easy to clean. When creating custom designs, be sure to choose granite for its superior benefits.

STANDARDS / HIGH WEAR APPLICATIONS
The granite utilized by ZhongHui for our standard surface plate products has high quartz content, which provides greater resistance to wear and damage. Our Superior Black and Crystal Pink colors have low water absorption rates, minimizing the possibility of your precision gages rusting while setting on the plates. The colors of granite offered by ZhongHui result in less glare, which means less eyestrain for individuals using the plates. We have chosen our granite types while considering thermal expansion in an effort to keep this aspect minimal.

CUSTOM APPLICATIONS
When your application calls for a plate with custom shapes, threaded inserts, slots or other machining, you’ll want to select a material like Black Diabase. This natural material offers superior stiffness, excellent vibration dampening, and improved machinability.

Yes, if they are not too badly worn. Our factory setting and equipment allow the optimum conditions for proper plate calibration and rework if necessary. Generally, if a plate is within .001" of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than .001" out of tolerance, or if it is badly pitted or nicked, then it will need to be sent to the factory for grinding prior to relapping.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. We urge you to use caution in selecting your calibration service. Ask for accreditation and verify the equipment that the technician will use has a National Inspection Institution traceable calibration. It takes many years to learn how to properly lap precision granite.

ZhongHui provides quick turn-around on calibrations performed in our factory. Send your plates in for calibration if possible. Your quality and reputation depend on the accuracy of your measurement instruments including surface plates!

Our black surface plates have a significantly higher density and are up to three times as stiff. Therefore, a plate made of the black does not need to be as thick as a granite plate of the same size to have equal or greater resistance to deflection. Reduced thickness means less weight and lower shipping costs.

Beware of others who use lower quality black granite in the same thickness. As stated above, properties of granite, like wood or metal, vary by material and color, and is not an accurate predictor of stiffness, hardness, or wear resistance. In fact, many types of black granite and diabase are very soft and not suitable for surface plate applications.

No. The specialized equipment and training necessary to rework these items requires that they be returned to the factory for calibration and rework.

Yes. Ceramic and granite have similar characteristics, and the methods used to calibrate and lap granite can be used with ceramic items as well. Ceramics are more difficult to lap than granite resulting in a higher cost.

Yes, provided that the inserts are recessed below the surface. If steel inserts are flush with, or above the surface plane, they must be spot-faced down before the plate can be lapped. If required, we can provide that service.

Yes. Steel inserts with the desired thread (English or metric) can be epoxy bonded into the plate at the desired locations. ZhongHui uses CNC machines to provide the tightest insert locations within +/- 0.005”. For less critical inserts, our locational tolerance for threaded inserts is ±.060". Other options include steel T-Bars and dovetail slots machined directly into the granite.

Inserts that are properly bonded using high strength epoxy and good workmanship will withstand a great deal of torsional and shear force. In a recent test, using 3/8"-16 threaded inserts, an independent testing laboratory measured the force required to pull an epoxy-bonded insert from a surface plate. Ten plates were tested. Out of these ten, in nine cases, the granite fractured first. The average load at the point of failure was 10,020 lbs. for gray granite and 12,310 lbs. for black. In the single case where an insert pulled free of the plate, the load at the point of failure was 12,990 lbs.! If a work piece forms a bridge across the insert and extreme torque is applied, it is possible to generate enough force to fracture the granite. Partially for this reason, ZhongHui gives guidelines for the maximum safe torque that can be applied the epoxy bonded inserts: https://www.zhhimg.com/standard-thread-inserts-product/

Yes, but only at our factory. At our plant, we can restore almost any plate to 'like-new' condition, usually for less than half the cost of replacing it. Damaged edges can be cosmetically patched, deep grooves, nicks, and pits can be ground out, and the attached supports can be replaced. In addition, we can modify your plate to increase its versatility by adding solid or threaded steel inserts and cutting slots or clamping lips, per your specifications.

Why Choose Granite?
Granite is a type of igneous rock formed in the Earth millions of years ago. The composition of igneous rock contained many minerals such as quartz that is extremely hard and wear-resistant. In addition to hardness and wear resistance granite has approximately half the coefficient of expansion as cast iron. As its volumetric weight is approximately one third that of cast iron, granite is easier to manoeuvre.

For machine bases and metrology components, black granite is the colour most used. Black granite has a higher percentage of quartz than other colours and is, therefore, the hardest wearing.

Granite is cost-effective, and cut surfaces can be exceptionally flat. Not only can it be hand lapped to achieve extremes of accuracy, but re-conditioning can be performed without moving the plate or table off-site. It is entirely a hand lapping operation and generally costs much less than re-conditioning a cast iron alternative.

These qualities make granite the ideal material to create custom-size and custom-design machine bases and metrology components such as the granite surface plate.

ZhongHui produces bespoke granite products that are created to support specific measurement requirements. These bespoke items vary from straight edges to tri squares. Due to the versatile nature of granite, the components can be produced to any size required; they are hard wearing and long-lasting.

Advantages of Granite Surface Plates
The importance of measuring on an even surface was established by British inventor Henry Maudsley in the 1800s. As a machine tool innovator, he determined that consistent production of parts required a solid surface for reliable measurements.

The industrial revolution created a demand for measuring surfaces, so engineering company Crown Windley created manufacturing standards. The standards for surface plates were first set by Crown in 1904 using metal. As the demand and cost for metal increased, alternative materials for the measuring surface were investigated.

In America, monument creator Wallace Herman established that black granite was an excellent surface plate material alternative to metal. As granite is non-magnetic and doesn’t rust, it soon became the preferred measuring surface.

A granite surface plate is an essential investment for laboratories and test facilities. A granite surface plate of 600 x 600 mm can be mounted on a support stand. The stands provide a working height of 34” (0.86m) with five adjustable points for levelling.

For reliable and consistent measurement results, a granite surface plate is crucial. As the surface is a smooth and stable plane, it enables instruments to be carefully manipulated.

The main advantages of granite surface plates are:

• Non-reflective
• Resistant to chemicals and corrosion
• Low coefficient of expansion compared with cart iron so less affected by temperature change
• Naturally rigid and hard-wearing
• The plane of the surface is unaffected if scratched
• Will not rust
• Non-magnetic
• Easy to clean and maintain
• Calibration and resurfacing can be done onsite
• Suitable for drilling for threaded support inserts
• High vibration damping

For many shops, inspection rooms and laboratories, precision granite surface plates are relied on as the basis for accurate measurement. Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining. They also are ideal bases for making height measurements and gaging surfaces. Further, a high degree of flatness, stability, overall quality and workmanship make them a good choice for mounting sophisticated mechanical, electronic and optical gaging systems. For any of these measurement processes, it is imperative to keep surface plates calibrated.

Repeat Measurements and Flatness
Both flatness and repeat measurements are critical to ensure a precision surface. Flatness can be considered as all points on the surface being contained within two parallel planes, the base plane and the roof plane. The measurement of distance between the planes is the overall flatness of the surface. This flatness measurement commonly carries a tolerance and may include a grade designation.

The flatness tolerances for three standard grades are defined in the federal specification as determined by the following formula:
Laboratory Grade AA = (40 + diagonal² / 25) x 0.000001 inch (unilateral)
Inspection Grade A = Laboratory Grade AA x 2
Tool Room Grade B = Laboratory Grade AA x 4

In addition to flatness, repeatability must be ensured. A repeat measurement is a measurement of local flatness areas. It is a measurement taken anywhere on the surface of a plate that will repeat within the stated tolerance. Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.

To ensure a surface plate meets both the flatness and repeat measurement specifications, manufacturers of granite surface plates should use Federal Specification GGG-P-463c as a basis for their specifications. This standard addresses repeat measurement accuracy, material properties of surface plate granites, surface finish, support point location, stiffness, acceptable methods of inspection and installation of threaded inserts.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

Checking Plate Accuracy
By following a few simple guidelines, an investment in a granite surface plate should last for many years. Depending on plate usage, shop environment and required accuracy, frequency of checking the surface plate accuracy varies. A general rule of thumb is for a new plate to receive a full recalibration within one year of purchase. If the plate is used frequently, it is advisable to shorten this interval to six months.

Before a surface plate has worn beyond specification for overall flatness, it will show worn or wavy posts. Monthly inspection for repeat measurement errors using a repeat reading gage will identify wear spots. A repeat reading gage is a high-precision instrument that detects local error and can be displayed on a high magnification electronic amplifier.

An effective inspection program should include regular checks with an autocollimator, providing actual calibration of overall flatness traceable to National Institute of Standards and Technology (NIST). Comprehensive calibration by the manufacturer or an independent company is necessary from time to time.

Variations Between Calibrations
In some cases, there are variations between surface plate calibrations. Sometimes factors such as surface change resulting from wear, incorrect use of inspection equipment or use of noncalibrated equipment can account for these variations. The two most common factors, however, are temperature and support.

One of the most important variables is temperature. For instance, the surface might have been washed with a hot or cold solution prior to calibration and not allowed sufficient time to normalize. Other causes of temperature change include drafts of cold or hot air, direct sunlight, overhead lighting or other sources of radiant heat on the surface of the plate.

There also can be variations in the vertical temperature gradient between winter and summer. In some cases, the plate is not allowed sufficient time to normalize after shipment. It is a good idea to record the vertical gradient temperature at the time the calibration is performed.

Another common cause for calibration variation is a plate that is improperly supported. A surface plate should be supported at three points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered.

Only three points can rest solidly on anything but a precision surface. Attempting to support the plate at more than three points will cause the plate to receive its support from various combinations of three points, which will not be the same three points on which it was supported during production. This will introduce errors as the plate deflects to conform to the new support arrangement. Consider using steel stands with support beams designed to line up with the proper support points. Stands for this purpose are generally available from the surface plate manufacturer.

If the plate is properly supported, precise leveling is only necessary if an application specifies it. Leveling is not necessary to maintain the accuracy of a properly supported plate.

It is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages. Cover plates to protect them from dust and damage. Wear life can be extended by covering the plate when not in use.

Extend Plate Life
Following a few guidelines will reduce wear on a granite surface plate and ultimately, extend its life.

First, it is important to keep the plate clean. Airborne abrasive dust is usually the greatest source of wear and tear on a plate, as it tends to embed in workpieces and the contact surfaces of gages.

It also is important to cover plates to protect it from dust and damage. Wear life can be extended by covering the plate when not in use.

Rotate the plate periodically so that a single area does not receive excessive use. Also, it is recommended to replace steel contact pads on gaging with carbide pads.

Avoid setting food or soft drinks on the plate. Many soft drinks contain either carbonic or phosphoric acid, which can dissolve the softer minerals and leave small pits in the surface.

Where to Relap
When a granite surface plate needs re-surfacing, consider whether to have this service performed on-site or at the calibration facility. It is always preferable to have the plate relapped at the factory or a dedicated facility. If, however, the plate is not too badly worn, generally within 0.001 inch of the required tolerance, it can be resurfaced on-site. If a plate is worn to the point where it is more than 0.001 inch out of tolerance, or if it is badly pitted or nicked, then it should be sent to the factory for grinding prior to relapping.

A calibration facility has the equipment and factory setting providing the optimum conditions for proper plate calibration and rework if necessary.

Great care should be exercised in selecting an on-site calibration and resurfacing technician. Ask for accreditation and verify the equipment that the technician will use has a NIST-traceable calibration. Experience also is an important factor, as it takes many years to learn how to correctly lap precision granite.

Critical measurements start with a precision granite surface plate as a baseline. By ensuring a reliable reference by using a properly calibrated surface plate, manufacturers have one of the essential tools for reliable measurements and better quality parts.

Checklist for Calibration Variations

1. The surface was washed with a hot or cold solution prior to calibration and was not allowed sufficient time to normalize.
2. The plate is improperly supported.
3. Temperature change.
4. Drafts.
5. Direct sunlight or other radiant heat on the surface of the plate. Be sure that overhead lighting is not heating the surface.
6. Variations in the vertical temperature gradient between winter and summer. If at all possible, know the vertical gradient temperature at the time the calibration is performed.
7. Plate not allowed sufficient time to normalize after shipment.
8. Improper use of inspection equipment or use of noncalibrated equipment.
9. Surface change resulting from wear.

Tech Tips
Because every linear measurement depends on an accurate reference surface from which final dimensions are taken, surface plates provide the best reference plane for work inspection and layout prior to machining.

Controlling local area flatness to a tighter tolerance than overall flatness guarantees a gradual change in surface flatness profile, thereby minimizing local errors.