An Introduction to Precision Machining of Technical Ceramics

Interview conducted by G.P. ThomasMay 15 2014

AZoM talks to Scott D. Mittl, Sales Engineer at Insaco, regarding the applications and benefits of diamond grinding technical ceramics.

How would you describe the type of machining operations Insaco can currently provide?

Insaco fabricates precision parts to customer specifications from most technical ceramics, by use of both fixed diamond abrasive wheels as well as free abrasives for lapping/polishing.

Insaco is a diamond grinding house, so we can work on any materials that are suitable for this technology.  Since we don’t produce materials, we will normally source what we need from the most appropriate producer, which might be governed by part size and volume capability, as well as lead time and price.

This is an advantage to our customers, as our discussion about the merits and concerns with some materials for their application is not biased by our own preference.

Can you machine all brittle materials or are you focused on a specific subset of materials?

Insaco will consider fabricating from both oxide and non-oxide ceramics and crystal materials.  We avoid metallics generally because they don’t respond as well to our diamond wheels.

Because diamond grinding wheels are so fine, we do not work with metals or plastics. There are also some technical ceramics that we try to avoid, such as BeO, AlN, Boron Nitride and some glasses due to environmental hazards with handling, swarf treatment or softness.

Insaco got our start 67 years ago machining sapphire for phonograph needles, so once precision grinding of sapphire was mastered, we were confident to add other available technical ceramics to our offerings.

Do you operate across all industry sectors or specialise in certain areas?

Precision machined ceramics are expensive, so only considered by designers for applications where conventional metals are not suitable. This means our customers are usually pushing the envelope for their application, putting them usually in high tech development.

This can be in any industry, so Insaco does not focus on any specific industry.  We supply to defense, aerospace, medical, semiconductor, instrumentation, life sciences industries among others.

Are there any limitations on sizes?

There are of course size limitations on certain machine tools.  However, usually such limitations will vary depending upon the size of the part itself as well as what other machining operations are required.  So, it is best to review an actual part drawing before deciding on feasibility.  Insaco does have a VMC (vertical machining center) for example with a large working envelope (120” x 70” x 32”).

Our 60” lap tables are designed to effectively work on part diameters up to 20”.  We have successfully polished larger or eccentric parts under special circumstances.

When customers are providing you with drawings and designs are there common mistakes that are made, for example design features that apply to a metal component that are difficult to replicate in Engineering Ceramics?

Insaco fabricates by diamond grinding and metals are usually fabricated by single point cutting.  A fillet radius when grinding is practically limited to no sharper than around .006” since wheels can’t be dressed much sharper and will immediately start to wear away upon touching ceramic.  Sharp internal corners can also be a spot where stresses concentrate that can lead to early failure in brittle ceramics.

Sometimes a drawing calls for a sharp fillet in order to accommodate a sharp mating part.  In this case Insaco will propose some design alternates for our customer to consider such as designing an undercut for clearance, or perhaps chamfering the mating part.

I appreciate much of your work is confidential but are there any jobs you are particularly proud of that you can talk about?

With literally hundreds of customers and applications supplied each year since 1947, Insaco has made key components for some very diverse technical achievements, from LED fabrication to mass spectroscopy.

Our parts have been integral to anti-missile defense systems, and also guidance systems and other key parts of projectiles.  We have parts on the Space Station related to the water reclamation system there.  Insaco supplies precision parts to several heart pumps both internal and external to the body, and for years made parts used in genome sequencing.  We have long been fabricating precision piston/sleeve combinations of several sizes and types that are used for metering pumps that run ceramic on ceramic, without seals.

Semiconductor processing involves harsh environments where avoiding certain elements as contaminants is vital.  Silicon Carbide and sapphire are often specified as best options and Insaco has long been involved supplying parts here and also as carriers for the Compound Semiconductor industry.  Ceramics are often specified by instrument makers due to required precision and stability and sometimes inertness.

Insaco makes ceramic collars to position rods in Quadrupole Mass Spectrometers for several manufacturers requiring tolerances to one micron. We also make guide and form rollers for metals and fibers processing.

About Scott D. Mittl

Scott D. Mittl, Sales Engineer, has been an employee of Insaco® since 1990 and is responsible for sales engineering activity including quotations and account management.

He takes an aggressive proactive approach to developing new customers and new product applications. This approach includes developing subcontractors to further enhance Insaco®'s machining capability in any non-metallic material.

He has the technical expertise and experience in materials to aid customers in successfully designing products out of materials commonly machined by Insaco®. He has a B.A. in Applied Sciences and a B.S. in Metallurgy and Materials Engineering from Lehigh University and is a member of the American Ceramic Society.