Ebonites machinability

In the plastics recovery section, the polypropylene is separated from other plastics and products such as PVC separators, ebonite cases, labels, rope handles, etc., via a series of classifiers and hydro-cyclones. The polypropylene pieces or chips are cleaned, washed, and separated from any remaining paste and dust. Once the material has been shredded to smaller fragments, the plastic is a valuable by-product of battery recycling. Plastic cleaning and processing methods are so effective that heavy metal contamination in the final polypropylene product is very low. The final product can be used in household goods such as washing machines, vacuum cleaners, and dishwasher parts, or in products for the automotive industry [5]. 

Ebonite can be machined and is often produced in bar, tube, or sheet stock for this purpose. Major applications make use of its chemical inertness and corrosion resistance as well as its electrical and thermal insulating properties. The material softens at about 50°C and, hence, is not suitable for high-temperature applications. 

Movement of the ram is necessary to prevent overloading of the drive motor. Many years ago the author went to see a 3A Banbury, used to mix hard ebonite stocks, because the motor driving the machine kept going into overload and stalling on every batch, although the machine had been used to mix the same compound easily for many years without overload. The fault was traced to a crack in the hopper cover which trapped the piston rod as the force from the mix thrust upwards, preventing movement of the ram. This caused the overload condition. 

The early history of telephony from the late 19th century onwards involved a limited range of insulating materials with rubber and ebonite most commonly employed by equipment designers. These materials were fashioned into components by many time-consuming machining operations. 

---