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Bakelite CNC Machining

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Bakelite CNC Machining

Bakelite is the first variety of plastics put into industrial production, Bakelite's chemical name is phenolic plastic, and it has high mechanical strength, good insulation, heat resistance, and corrosion resistance, so it is often used in the manufacture of electrical materials, such as switches, lamp heads, headphones, telephone cases, instrument cases, etc., "Bakelite" thus named. The introduction of Bakelite is of great significance to industrial development.



Mechanical properties


Phenolic plastic is a hard and brittle thermosetting material.

Bakelite's characteristics are non-absorbent, non-conductive, high-temperature resistance, and high strength, and is used in electrical appliances, and is called "Bakelite" because it is highly insulating and malleable like wood. Bakelite is made from powdered phenolic resin, mixed with sawdust, asbestos, or clay, and then pressed into a mold at a high temperature to produce a finished product.

Phenolic plastic (Bakelite): hard surface, brittle and fragile, knocking with the sound of wooden boards, mostly opaque dark color (brown or black), does not soften in hot water. It is an insulator, and its main component is a phenolic resin.


Molding performance


1. Molding properties are better, but shrinkage and directionality are generally larger than that of amino plastics, and contain moisture volatiles. It should be preheated before molding and exhausted during the molding process, and the mold temperature and molding pressure should be increased without preheating.

2. Mold temperature has a large impact on the fluidity, generally over 160 degrees, the fluidity will decline rapidly.

3. The hardening speed is generally slower than that of amino plastics, and the heat released during hardening is large. The internal temperature of large thick-walled plastic parts is easily too high, and uneven hardening and overheating will easily occur.

When formaldehyde/phenol (molar ratio) is less than 1, thermoplastic products can be obtained, called thermoplastic phenolic resin, that is, linear phenolic resin, which does not contain further condensation of groups, plus curing agent and heating to cure. Such as hexamethylenetetramine as a curing agent, curing temperature of 150 ℃, mixed with fillers made of molding powder commonly known as Bakelite powder. When formaldehyde/phenol (molar ratio) is greater than 1, in the alkali-catalyzed first to get a stage A resin, that is, thermosetting phenolic resin, soluble in organic solvents, A stage resin contains hydroxymethyl can be further condensed, so no need to add a curing agent that can be cured: the reaction under heating to get B stage resin, also known as semi-soluble phenolic resin, insoluble and non-melting but can be swollen and softened. The further reaction gives the insoluble and non-melting bulk structure C-stage resin, also known as insoluble phenolic resin. Stage A resin can also be cured by itself in long-term storage.

The curing form of thermosetting phenolic resin is divided into two kinds of room temperature curing and heat curing. Room temperature curing can be used non-toxic room temperature curing agent NL, which can also use benzene sulfonyl chloride or petroleum sulfonic acid, but the latter two materials are more toxic, and irritating.


                                                                 

Last updated on 247640784

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