Best Practices for Machining HYTAC® Plug-Assist Materials

Machining syntactic foam is not like machining other materials such as wood, aluminum or plastic. That’s why we have created guides to help toolmakers and thermoformers select the right tools and the right geometry for machining and cutting HYTAC® syntactic foams from CMT.

Properly machined, HYTAC® materials generally require minimal extra polish or surface preparation.  Following our guidelines will improve surface quality of the finished plug and aid consistency of plug performance.

Tools must be sharp to obtain a satisfactory surface finish when machining HYTAC® products. High helix geometry with a special point for upward chip flow, smooth sidewall and improved bottom finish is recommended. Dull cutters or incorrect geometries will result in poor surface conditions. High speed steel cutters are quickly dulled and are not suitable for use with syntactic foams. Solid carbide cutters are preferred due to the sharp edge and long life that may be obtained. Diamond coated tools may last longer, but are not required and have not been found to provide additional benefit in machining.

Once the tool is selected, dialing in an optimal feed rate on any CNC milling machine is done using the formula “Feed Rate = Chip Load x Spindle RPM x # of flutes.”  Chip load is the measure of thickness removed by each cutting edge (flute) in a single rotation.  The intended chip load for milling tools should be available from your tool supplier.  Optimal speeds, feeds and depth of cut when turning are listed on our turning guide.

If you have a new  job or just some questions about plug machining or polishing, contact us today