What is Paper Bakelite?

What is Paper Bakelite?

Paper Bakelite is a thermosetting laminated material valued for its excellent heat resistance, mechanical durability, and affordability.

What sets it apart from other plastics is its laminated structure. The strength of the material varies depending on whether force is applied vertically or horizontally to the laminated layers.

It has strong resistance to vertical loads but weaker resistance to horizontal loads. It also offers excellent dimensional stability with little warping. However, it does have a relatively high water absorption rate, meaning some dimensional changes may occur due to moisture or water uptake.

Mechanical Strength

With a flexural strength of 98 MPa (vertical direction) and a tensile strength of 65 MPa (vertical direction), its performance is comparable to that of engineering plastics like POM. However, its impact resistance is relatively low, with an Izod impact strength of 21 to 40 J/m. Because of this brittleness, cracking and chipping may occur under impact or during machining, requiring extra care during processing.

Heat Resistance

Paper Bakelite has excellent heat resistance, with a continuous service temperature of approximately 130°C, which is higher than many common engineering plastics.

Flame Retardancy

According to the UL94 standard, Paper Bakelite is rated HB, meaning it is slow-burning. While it does not self-extinguish, it is not easily flammable. There are also specialized flame-retardant grades, such as V-0-rated Bakelite, which offer higher resistance to ignition and self-extinguishing properties.

Insulation

Paper Bakelite has high electrical resistivity, making it an effective insulator. While super engineering plastics can provide even higher levels of electrical resistance, Bakelite offers sufficient insulation performance for most applications.

Chemical Resistance

Bakelite demonstrates good resistance to many chemicals. However, it is less resistant to acrylic solvents, strong acids, and strong alkalis. When these chemicals are likely to be present in an application, it is important to confirm compatibility with the manufacturer’s material specifications in advance.

Usage & Machining Considerations

Bakelite is a hard but brittle material that is prone to chipping. During machining, proper cutting speeds and attention to the lamination direction are essential. Cutting generates a large volume of fine dust, and although tolerances of up to 0.01 mm can be achieved, tool wear becomes a limiting factor in maintaining precision during large production runs.

Prolonged machining with the same cutting tool can lead to dimensional inaccuracy, heat buildup, and even surface burning or deformation. Due to its high water absorption, it is generally best to avoid machining with liquid coolants. For these reasons, Bakelite is considered more challenging to process compared to other plastics, requiring careful tool selection and machining methods.

Appearance

The top and bottom surfaces are smooth and glossy. Over time, the color darkens due to oxidation, but this has no impact on material properties. Standard colors are brown and black.

Applications

• Insulating base plates

• Various insulating components

• General-purpose industrial parts

Gear Machining

Gears are typically machined from round bar stock. However, when machining gears from Bakelite, sheet stock is often preferred. This is because Bakelite’s laminated structure influences performance in gear applications.

Round bar stock has a layered structure similar to that of tree rings. When gears are machined from round bars, the gear teeth are subjected to forces parallel to the lamination, which can cause premature failure. By contrast, machining gears from sheet stock allows the load to be applied vertically to the laminated surface, fully utilizing Bakelite’s strength and reducing the risk of tooth breakage.

Compatible Machining Methods

• Cutting

• Bonding

• Painting

Examples of Bakelite Applications

Electrical and Electronic Components

With excellent insulating and heat-resistant properties, Bakelite is widely used for components such as distribution boards, circuit breakers, insulating terminal boards, and transformer parts. Its combination of low cost and durability makes it ideal for applications where electrical insulation and heat resistance are critical.

Semiconductor Manufacturing Equipment

Bakelite is also used in semiconductor production equipment. Its mechanical strength, lightweight nature, insulation properties, and affordability make it well-suited for balancing performance with cost efficiency in machinery design.

Size Availability Chart

Major Manufacturers

Futamura Chemical Co., Ltd.

Step Up Your Project with Yumoto Electric

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If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.