All materials expand and contract as temperatures change. Honing and grinding tubing and bars generate heat from these processes. Knowing how much a rise in temperature will change a machined component allows Commercial Fluid Power to quickly produce materials with great accuracy and outstanding quality.

All measurements are based on an ambient temperature of 68 degrees Fahrenheit.  Deviations from this temperature will cause material to contract or expand in a predictable manner. 

I have an Excel spreadsheet available that will calculate the coefficient of thermal expansion for some of the common grades of material used in the fabrication of hydraulic and pneumatic cylinders.  This spreadsheet can build a table for a given size and grade from 32 degrees F to 139 degrees Fahrenheit in a few easy steps.  If you are interested in receiving a copy of this spreadsheet please e-mail me at: BobRick@CommercialFluidPower.com

Checking temperature on a piece being machined is now safe, easy and accurate.  There are non-contact temperature gages available on line and in hardware stores for under $50.00. The KINTREX IRT0421 Non-Contact Infrared Thermometer with Laser Targeting is available through Amazon.com that has an accuracy reading of +/- 2% and a measurable temperature range from 32 to 932 degrees Fahrenheit.

Commercial Fluid Power understands that the growth of material is critical in producing a quality part that will function in the freezing sub zero temperatures of the Arctic or the unrelenting intense heat of a desert.  This is becoming more and more critical as our products reach end users across the Globe.

 A carbon steel tube with a 12.000" ID tube will grow dimensionally slightly more than 0.004" at 120 degrees Fahrenheit.  A tube being honed can reach temperatures of anywhere from 90 to 120 degrees or more depending on many factors such as coolant temperature or how aggressive the operator is removing stock. 

A 12.000" tube will typically have a tolerance of 0.005" or less.  Temperatures of 120 degrees will take up more than 80% of the tolerance.  A Hone Operator will adjust his finished HOT size to shrink into tolerance when the tube reaches ambient temperature or 68 degrees.

Different materials will grow at different rates.  The 12.000" carbon steel tubes will grow 0.0041" at 120 degrees.  The same 12.000" tube in Aluminum would have a growth rate of 0.0081" or in a 304 SS grade would grow 0.006".  Understanding thermal expansion is a key component in quality as well as keeping cost competitive.

Understanding thermal expansion and material grade a Hone Operator can finish a piece at a HOT size and break off a setup and move on to the next job with confidence knowing that the thermal expansion of a particular size and material grade will meet the Customer tolerance specification.  This same expansion can be applied to any machine operation that generates heat.

If you have any questions please call or e-mail and I will be glad to help.  If you would like to see more information on any of our products or services in a future newsletter please e-mail your comments or suggestions to BobRick@CommercialFluidPower.com  Thanks for reading. Have a great day!