production economics do not merit the expense of melt processing. The material is free-cutting, but does require sharp tools with a high clearance angle. The use of soluble cutting lubricant is not necessary, but is recommended. POM sheets can be cut cleanly and accurately using an infrared laser, such as in a CO2 laser cutter. Because the material lacks the rigidity of most metals, care should be taken to use light clamping forces and sufficient support for the work piece. As can be the case with many polymers, machined POM can be dimensionally unstable, especially with parts that have large variations in wall thicknesses. It is recommended that such features be "designed-out" e.g. by adding fillets or strengthening ribs. Annealing of pre-machined parts before final finishing is an alternative. A rule of thumb is that in general, small components machined in POM suffer from less warping. Bonding POM is typically very difficult to bond, with the copolymer typically responding worse to conventional adhesives than the homopolymer. Special processes and treatments have been developed to improve bonding. Typically these processes involve surface etching, flame treatment, using a specific primer/adhesive system, or mechanical abrasion. Typical etching processes involve chromic acid at elevated temperatures. DuPont uses a patented process for treating acetal homopolymer called satinizing that creates a surface roughness sufficient for micromechanical interlocking. There are also processes involving oxygen plasma and corona discharge. In order to get a high bond strength without specialized tools, treatments, or roughening, one can use Loctite 401 prism adhesive combined with Loctite 770 prism primer to get bond strengths of ~1700psi. Once the surface is prepared, a number of adhesives can be used for bonding. These include epoxies, polyurethanes, and cyanoacrylates. Epoxies have shown shear strength. Cyanoacrylates are useful for bonding to metal, leather, rubber, cotton, and other plastics. Solvent welding is typically unsuccessful on acetal polymers, due to the excellent solvent resistance of acetal. Thermal welding through various methods has been used successfully on both homopolymer and copolymer. Usage Mechanical gears, sliding and guiding elements, housing parts, springs, chains, screws, nuts, fan wheels, pump parts, valve bodies. Electrical engineering: insulators, bobbins, connectors, parts for electronic devices such as televisions, telephones, etc. Vehicle: fuel sender unit, light/control stalk/combination switch (including shifter for light, turn signal), power windows, door lock systems, articulated shells. Model: model railway parts, such as trucks (bogies) and hand rails (handle bars). POM is