Processing:
The machining of CMP semi-finished products and, in general, of all products in thermoplastic materials, must be carried out following special precautions. It is notoriously known that plastics are softer than steel but this does not mean that they are easier to cut, drill or work with.
One of the major problems is the choice of the tool so that the disposal of the accumulated temperature, due to its friction, does not lead to the tensioning of the semi-finished product with consequent breakage or reduction of the mechanical characteristics of the piece under processing.
Tools
Tools are generally the ones used for soft metals, but in order to avoid continuous sharpening of the tools can be used those of hard metal, with the same cutting and rake angles, whose sharpening must be accurately finished. Tools already used for metalworking must be re-sharpened before being used in processing the product.
Turning
Turning, milling and drilling operations are performed at low speed with little pushing. Due to the low thermal conductivity of these materials, cooling is always recommended. You can use: oil, emulsified oils, soapy water. Fog cooling - with compressed air or sprayed refrigerant - can also be effective.
Method
The chippings must be continuously removed to prevent them from getting wedged between the tool and the workpiece, so it is necessary to maintain a large cutting section and use tools that leave plenty of room for chip removal. During the drilling operation it is necessary to remove the tip from time to time to facilitate the evacuation of the chips. In deep holes, lubricated tips are recommended. Since holes of a considerable diameter must be made, it is advisable to start with smaller diameter spikes and gradually widen them with larger diameter spikes
Remark!
During cold seasons, before you start drilling, we recommend you to preheat the pieces at 20-30 oc in an proper space.
Information
- All Information given refer to test conducted at normal temperatures. 23°( - 50% U.R.).
- Material properties depend on operating temperatures: they decrease with the increasing of heat.
- A continous operating temperature of 100° C reduces material properties by approximately one-half.
- Descriptions, data and information contained herein is provided for your guidance only, they are not guaranteed values and we do not assume any responsibility regarding the contents and information supplied.
Tolerances
Before finishing pieces and to obtain desidered tolerances, it would be better let them get cold at room temperature. In establishing tolerances, it is necessary to take into consideration the effect of elasticity and hygroscopicity on materials thant affect dimensional stability. it is necessary to know that plastic materials need larger tolerances than metals.
