Phenolic Machined Parts

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Importantly, Sentinel has been Manufacturing Phenolic Machined Parts for over 30 years. This experience is just one of many reasons why we consider ourselves top of the pack in this field. The company has the skills and the depth of knowledge required to CNC Machine the variety of phenolics available today.

What is Phenolic?

Phenolics are produced when laminates, made from layers of paper, cotton cloth or glass fibre cloth, are placed into a resin or varnish and then strongly bonded together.

In addition, to squash the layers together, the laminated contents of the press are heated up under a very high pressure. As this happens, the resin melts and becomes gluey, sticking the layers firmly together into one solid mass. Whilst still under the heat and pressure, the resin then ‘cures’, that is, it undergoes a chemical change, becoming a hard, solid material which can no longer be melted with heat.


Tufnol Phenolic Machining UK


By using different varieties of resin with various types of cloth or paper, many different grades of industrial laminates can be produced.

The three main types are:-,
Phenolic Machined Parts made from layers of paper – known as SRBP, or ‘synthetic resin bonded paper’.
Also, Phenolic Machined Parts grades made from layers of cotton cloth – known as SRBF, or ‘synthetic resin bonded fabric’
Finally, epoxy glass laminate, which is the most common, grades are made from layers of glass fibre cloth.

Common Trade Names: Tufnol, Paxolin, Bakelite, Bakelaque, Garolite, Micarta, Pertinax, Pirtoid. Furthermore, specialist Phenolic laminates, such as low smoke and halogen free materials are available. For example, EM42.

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Methods of Machining Phenolic


First of all, it’s important to note that Phenolic Machined parts can be manufactured from sheet, rod or tube. As a result, the type of part required will then dictate the material requirement and the method of manufacture.

Sentinel Plastics Ltd can draw on many years’ experience to produce high precision components from high specification industrial plastics materials.

Phenolic CNC Milled Parts, CNC Turned Parts (Rod or Tube) and finally CNC Routing flat Sheet. Most noteworthy, a large capacity of machinery is available to Sentinels experienced and highly skilled staff. This ensures the customer can be confident of a relatively short lead time and quality of parts supplied. Specifics on these methods can be found through clicking on the linked names, or on the top menu.


Phenolic Industrial Laminate Fabrication and Finishing


Certainly, with the correct adhesive or resin, Industrial Laminates can be easily bonded. Customer commonly used applications are electrical wire bobbins or switchgear and power control base plates. The excellent mechanical strength combined with its insulation properties make phenolics the popular choice for fabricated electrical assemblies.

The final process in the manufacture of Phenolic industrial laminate components is heat treatment and varnish or resin coating. The experienced Sentinel Plastics team regularly carry out these processes.


Phenolic Machined Parts manufactured here at Sentinel.


Tufnol 6F/45 Machining Industrial Plastics Industrial Plastics - 6F/45 Tufnol Materials - Phenolic Machined PartsEpoxy Glass Machining Tufnol Turned Parts Phenolic Machined Parts
Insulation Plastics

SRBP – Phenolic – Tufnol – Insulation Plastics


Epoxy Glass

Firstly, the make up of G10-FR4  materials are an Epoxy Glass based Insulation Plastic. Laminates generally offer high mechanical strength and dimensional stability, are extremely durable, and maintain their properties wet or dry. Therefore the result of this blend is a material that offers excellent ark and track resistance.


The commonly known G10-FR4 are the most popular grades. G10-FR4 glass cloth reinforced epoxy natural is typically a yellowish to light green color. Epoxy resins are among the most versatile and widely used plastics in the electronics field, primarily because water absorption is virtually nil, rendering it an outstanding insulator.

As a result of being the most economic choice of G10-FR4 material, it is also noteworthy for being a material which can be easily machined to bespoke applications.

Some examples of what G10-FR4 Materials are widely used to manufacture are Insulating supports, high voltage insulation, bus bar supports and mounting panels in electrical apparatus are just some examples.


Based on the needs of its particular application it comes in several grades.

So there are many advantages to using G10-FR4 Machining Materials. Most of all having high structural strength but also excellent Electrically Insulating properties.
Most noteworthy, raw materials are available in standard sheets & rod sizes.
Finally a couple of important factors. Firstly Sheet thickness ranges from 0.8mm to 50mm.

Sentinel Plastic Engineering Only Supplies Bespoke Parts

All phenolic machined parts manufactured by Sentinel Plastics Ltd are customer specific bespoke plastic cutting parts. Either working from Prototypes, drawings, making a One off or hundreds of parts. Sentinel Plastics has flexibility to meet most requirements.

As well, the material is nearly immune to shrinkage, holding its form factor and dimensional stability at temperatures as high as 285° F. This property makes it ideal for use in electronic equipment with components that generate excessive heat. Should it combust at higher temperatures, the bromine added during the manufacturing process renders it self-extinguishing, another important factor for making its use in aerospace engineering so prominent.

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