MACHINING Vical acrylic ACRYLIC SHEET

The usual rules of good machining practice apply to the machining of Vical acrylic. An experienced machinist will have no difficulty handling Vical acrylic as soon as he gets the "feel" of the material. Vical acrylic has working qualities similar to those of brass and copper.

Tools and work should be held firmly to prevent chattering. Standard metal or wood working equipment can be used, such as milling machines, drill presses, lathes, planers and shapers. In general, machining tools should be operated at high speeds with slow feed rates. Tools should be sharp, clean and free of nicks and burrs.

Because it is a thermoplastic material, Vical acrylic softens when heated to its forming temperature. The frictional heat generated by machining tends to soften Vical acrylic in the immediate vicinity of the cut and causes gumming and sticking of the tool or tearing of the plastic if excessive heat build­up occurs. When proper speed, feed and cutters are used, machined Vical acrylic surfaces will have an even, semi­matte surface which can be brought to a high polish by sanding and buffing.

If tools are sharp and properly ground, coolants are seldom required for machining Vical acrylic. They may be desirable for unusually smooth finish or for deep cuts. If coolants are employed, only detergent in water or 10% soluble oil in water should be used. Other coolants may contain chemicals harmful to Vical acrylic.

Vical acrylic sheet can be machined to close tolerances and finished parts should be annealed. For applications which require both close tolerance and good optical properties, such as periscope prisms and lenses, Vical acrylic blanks should be annealed before and after rough machining. The parts may then be machined to close tolerance, removing as little material as possible. When final machining is complete, the parts should be given a final annealing. Since temperature and humidity affect the dimensions of Vical acrylic, machining to close tolerance must be done under conditions like those which will prevail when the parts are tested and put into service.

Vical acrylic acrylic plastic is a combustible thermoplastic material. Observe fire precautions appropriate for comparable forms of wood and paper Products.

1. TURNING, ROUTING & SHAPING
2. DRILLING
3. TAPPING AND THREADING

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