The Ultimate Buyer's Guide for Purchasing Granite Surface Plate

Do you have any idea about granite surface plates? Granite is a durable and hard stone that finds its uses in different sectors. One of its most common and popular applications is precision assembly devices like granite surface plates.

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Granite surface plates are stable, flat, and reliable surfaces that assemble precision parts. These plates hold great importance in sectors like engineering, manufacturing, and laboratory-based research.

This blog aims to shed light on the benefits and drawbacks of using granite surface plates. Contact a reputable helicoil thread repair kit supplier in Dubai, UAE, to buy authentic granite surface plates at a reasonable rate.

Definition of Surface Plates

Surface plates are plain, flat surfaces utilized as a horizontal reference space for dimensional measurement. Surface plates are the base for tool making, inspection, spotting, gauging, layout making, etc.

These plates are varied based on the materials. Working as a benchmark for all measurements, Surface plates are vital in both quality checking and control. These plates are extremely flat and include Grade-0 to Grade-3 thickness.

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There are three types of surface plates depending on the materials.

• Cast iron surface plates
• Granite surface plates
• Glass surface plates

Benefits of Granite Surface Plates

Among all these three variations, granite surface plates are the most beneficial. But why? Read the below points to know the real reasons.

Stability

One of the key boons of using granite surface plates is their extraordinary stability. Granite is a dense, hard material that doesn’t deform, bend, or warp easily, even under heavy weights. This feature makes these plates effective for precision-related uses. By the way, any precision-related work requires a flat surface for accurate readings.

Flatness

The next significant benefit of using granite surface plates is their flatness. Granite is an inherently rigid component with a uniform grain structure. It makes granite plates extremely flat. Hence, when a person positions precision parts on these tables, they get a flat and stable surface to rest. It is important to mention that a flat and rigid surface is necessary for precision assembly.

Corrosion-resistant

Do you know that granite has a great resistance against all sorts of chemicals? Yes, granite as a material is resistant to certain chemicals, alkalis and acids. This feature ensures the surface remains intact even after exposure to corrosive substances and harsh environments. Are you in search of authentic spare parts? Contact a renowned Mitutoyo original spare parts supplier in Dubai, UAE.

Durability

Durability is one of the most notable features of granite surface plates. Granite surface plates are durable and can resist heavy usage without deterioration. Unlike polypropylene of wooden surface plates, granite plates can resist scratches, chips, and dents. For this reason, they are ideal for high-traffic areas.

Aesthetics

Are you looking forward to offering your work area an attractive yet professional appearance? If yes, then granite surface plates are ideal for your needs. These plates can blend with the other equipment in your work area in a seamless manner.

Keeping a granite surface plate in your work area means enhanced workspace aesthetics. No matter what type of surface plates you want, contact any reputable cast iron surface plate supplier in Dubai, UAE.

Drawbacks of Granite Surface Plates

Though efficient and beneficial for different uses, granite surface plates have some drawbacks, too. What are they? Let’s have a quick look.

• Granite surface plates are too heavy, which sometimes makes them difficult to move.
• In comparison to other surface plates, granite plates are more expensive.
• Granite surface plates require regular maintenance and cleaning to retain their luster and looks.
• Though granite is a tough and rigid component, granite surface plates can easily get scratches, chips, and cracks.

FAQs

What are the different types of surface plates?

There are three types of surface plates: cast iron surface plates, granite surface plates, and glass surface plates. You can buy any of them from a cast iron surface plate supplier in Dubai, UAE.

What are the uses of surface plates?

The surface plates are crucial for geometric tolerance checking, calibration, layout, assembly etc.

What are the advantages of granite surface plates?

Granite surface plates are popular because of their stability, corrosion resistance, durability, flatness, and aesthetics.

What are the uses of surface plates in workshops?

The uses of surface plates in workshops are inspection, marking, tooling setup, dimensional measurement, wattage identification, etc.

Final Thoughts

So, the benefits of using granite surface plates outweigh the drawbacks. Granite plates offer a flat and stable surface essential for precise assembly. Businesses that prioritize quality assurance can use these plates.

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Surface Plates are solid flat plates used to mimic a perfect 2D plane as accurately as possible to facilitate other measurements being made on top that plane. Typical uses are precision inspection (for quality control, for example), marking out (putting precise markings to guide machine work), and tooling setup.

Many of the most common measurements are done with a Height Gauge.  A Surface Plate with height gauge is an extremely handy thing for any CNC'er or machinist to have on hand, so I recommend getting the set relatively early on.

Surface Plate Material: Granite, Cast Iron, Steel, or Glass

Surface plates are usually made of granite, and they come in a variety of sizes and grades.  There are cast iron, steel, and glass surface plates available, but most prefer to stick with granite.

Granite came into wide use during World War II.  Before that time, most surface plates were metal.  Granite surface plates were conceived as a means of saving the metal for more critical applications.  The idea to use granite came about by the happy coincidence of Wallace Herman owning both a monument and a metal shop in Dayton, Ohio.

Granite has a number of advantages over cast iron.  It's more durable and won't rust.  These advantages are why granite surface plates stayed popular even post-World War II.

You can find both black and pink granite used to make surface plates, with black granite being more popular.  Pink granite has more quartz, and therefore more wear resistance than black granite.  Quartz is more than twice as resistant to wear as the other minerals in granite.  However, Pink Granite isn't as strong as Black Granite and so it is normally desirable for a pink granite surface plate to be thicker.  Black Granite has superior stiffness, vibration damping, and machinability.

Before granite surface plates became prevalent, Cast Iron was the most common material for surface plates.  It is still popular for certain applications because it is easier to work it to a particular degree of precision than granite.  In fact, cast iron surface plates may be used as a tool to help lap (resurface) a granite surface plate.

Surface Plate Grades and Precision

Surface Plate Grades determine their flatness.  Standard grades include:

• AA (Most accurate):  These are referred to as laboratory grade.  Their flatness is (40 + diagonal (inches) of surface plate squared / 25) x 0.".
• A: These are Inspection Grade.  They're the AA spec x 2.
• B: These are Toolroom Grade.  They're AA x 4.
• Workshop Grade (Least accurate):  These are not really suitable for CNC applications, so I won't quote a spec.

Try to purchase an "A" grade granite surface plate in the largest size that you can afford and that fits comfortably in your shop.  This grade is intended for inspection work (quality control), and so covers the broadest range of use.

The ASME (American Society of Mechanical Engineers) has published ASME B89.3.7 - which is the current standard for granite surface plates.

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All surface plates must be calibrated regularly to ensure their accuracy has not been compromised by chipping, warping, or excessive wear.

The flatness of a surface plate is defined by two parallel planes-the base plane and the roof plane.  The distance between the two planes is the overall flatness.

Standard Surface Plate Sizes

Standard surface plate sizes are 18 x 24 in., 24 x 36 in., 36 x 48 in. and 48 x 72 in, but you can get most any size custom made if need be.  I have an "A" Grade 24 x 36 in A Class granite surface plate for my metrology needs.  It's a very nice surface plate for a small shop, but larger shops will want even larger surface plates and will likely have more than one.

Reducing Wear, Cleaning, and Extending Life of Granite Surface Plates

Reducing wear is all about keeping granite surface plates clean.  Airborne abrasive dust is the greatest source of wear, and it will also tend to embed in work pieces and the contact surfaces of gages.

Cover your plate to protect it from dust and damage.  Rotate it periodically so that wear isn't always in the same place.  Wherever possible use carbide pads on gauging as it is much less likely to have embedded abrasive dust.

Surface Plates should also be kept as clean as possible.  Swarf and other debris can easily interfere with accurate measurements.  Special Surface Plate cleaner is available relatively cheaply (about $30 on Amazon for a gallon) and should be used to prevent any chemical erosion of granite surface plates.

Ideally, clean your plate at the beginning and end of the day with appropriate cleaner.  Note that the evaporation of the cleaner can cause chilling, which may distort the surface.  Allow an hour for small plates to normalize and 2 hours for large plates.

Depending on how porous the granite in your plate is, retaining water from cleaning can be an issue that makes precision tooling more likely to rust.

Surface Plate Calibration

Surface Plates can experience chipping, warping, and just plain wear, so they must be calibrated regularly.  Often, the wear will be localized due to a particular tool, such as a height gauge, being used in the same place constantly.

Here's a fascinating video that walks through the process of testing and calibrating a surface plate in the field:

A process called lapping can be used to increase the flatness of a plate as needed.

Don't Use Your Surface Plate as a Counter!

Surface Plates are not counters.  Don't set anything on the surface plate other than gages and the pieces being measured.

Say you let someone put a Coke can on a Surface Plate.  That can may have dribbled so there's a little Coke on the bottom of the can.  But Coke is acidic and it will eat into your Surface Plate, damaging it.

Placing random things on Surface Plates can also transfer harmful debris that upsets delicate precision and abrades the Surface Plate.

Surface Plate Accessories

There is a huge variety of accessories used with surface plates.  We won't try to cover them all, just the most commonly used ones.

Ledges and Threaded Metal Inserts

Ledges are a part of the surface plate and must be specified when you order your plate.  Ledges are used to facilitate work clamping.

Threaded metal inserts may be embedded in the granite to facilitate clamping.  Keep the metal below the level of the granite to facilitate accuracy.

Surface Plate Stands

Proper support is essential for surface plates to minimize warping.  Granite Surface Plates should be supported at 3 points, ideally located 20% of the length in from the ends of the plates.  A precision surface can only be supported accurately by 3 points, not 4 or more.

A variety of stands are available to support all types of surface plates.  Smaller surface plates can be placed on any bench, but larger plates benefit from proper suspension.

Here's a typical fabricated stand for the sort of large surface plates found in the inspection and quality departments of many machine shops:

Temperature Controlled Room

It doesn't do you much good to specify a laboratory grade surface plate and then keep it in a room that isn't temperature controlled.  For the highest degree of accuracy and repeatability, the temperature must be consistent.  That's why so many shops keep their surface plates in a temperature controlled inspection room.

Surface Plate Covers

If your surface plate is not in continuous use (most are in commercial shops), it's nice to protect it with a fitted cover:

Surface Plate Cleaner

Special Surface Plate cleaner is available relatively cheaply (about $30 on Amazon for a gallon) and should be used to prevent any chemical erosion of the plate.

Height Gauges, Sine Gauges, and Gauge Blocks

Height Gauges, Gauge Blocks, and Sine Gauges (Sine Bars and Sine Plates) are probably the most common measuring accessories used with a surface plate, though there are many more.

This article is part of our Complete Guide to Metrology.