Choice of materials for your plastic injection moulded parts

There are two major categories of plastic materials on the market: thermoplastics and thermosetting plastics. They behave differently when exposed to heat.
Therefore, the material is key when designing and selecting the tooling. It is important to note that it is the material that forms the plastic part.


The most widely used thermoplastics

There are more than 60 different thermoplastic materials, but at Bülte we are only interested in the thermoplastic polymers featuring in our catalogue. Below are the characteristics of the main thermoplastics used by Bülte given that, for each raw material manufacturer, the properties vary depending on the type of material and also on the adjuvants, additives and mixtures, etc. Depending on the part purchased, we will be able to provide you with a sheet setting out the specific characteristics of the product material.

Bülte : matériaux et polymères thermoplastiques

Standard thermoplastics

❖ PA 6 -Polyamide 6

Strengths :
- low coefficient of friction
- Good mechanical properties
- Good thermal resistance
- Good electrical insulation


Weaknesses :
- opacity
- UV-sensitive
- brittle when dry
- poor acid-resistance


Applications :
In general, technical components for industry, the electricity and automotive sectors


❖ LDPE - Low-density polyethylene

Strengths :
+ food grade
- flexible and elastic
+ high chemical inertia
no moisture absorption    


Points faibles :

Applications :

❖ HDPE – High-density polyethylene

Strengths :
- identical to LDPE
- greater rigidity than LDPE (hard/elastic)
+ chemical resistance
- Non-stick
+ high impact resistance
+ good performance at high temperatures


Weaknesses :
- Difficult to bond
- little mechanical strength
- Cracks easily under stress
- poor heat resistance


Applications :
Specifically used in the production of cling film, flexible hoses/pipes, toys, squeezable bottles, etc.


Engineering plastics

❖ PA 6 GF30 – Polyamide 6 with 30% glass fibre

This is an injection moulding material reinforced with glass fibre thermoplastic polymers reinforced with glass fibre markedly improve the mechanical, thermo-mechanical and dimensional performances of manufactured parts while retaining the same injection moulding techniques as standard thermoplastics.


Strengths :
- Very good resistance to hydrocarbons, alkaline substances, grease, oil, fuel, ethers, esters, ketone.
- good wear resistance
- High rigidity
- high strength
- high dimensional accuracy


Weaknesses :
- not resistant to halogens, mineral acids and certain organic acids, oxidising agents


Applications :

❖ PP – Polypropylene:

Strengths :
+ High rigidity
+ Food grade
+ Good chemical resistance
+ Good resistance to high temperatures
+ Good bending strength, hinge effect
+ Good mechanical strength, rigidity


Weaknesses :
- Difficult to bond
- High-frequency welding
- Brittle at low temperatures


Applications :
PP has similar applications but with better mechanical strength


PVDF-Polyvinylidene fluoride :

Strengths :
+ high chemical resistance to numerous oils, greases, alkalis and saline solutions, even at high temperatures
+ high mechanical strength and toughness
High wear resistance
UL94V-V0 (UV-resistant – low ageing)
+ excellent thermal stability


Weaknesses :
- Operating temperatures from -20C to +130 C


Applications :
Mainly used in critical applications, which require excellent chemical resistance, high purity and outstanding mechanical properties.
PVDF is used as an insulator or a protective barrier in the chemical industry.


PTFE – Polytetrafluorethylene

Strengths :
+ Excellent chemical resistance


Points faibles :

Applications :
Often used in the medical, aviation and aerospace sectors, the oil industry, the petrochemical and food industries, packaging and kitchen utensils (by Tefal for example)


PEEK- Polyetheretherketone

PEEK thermoplastic is generally considered one of the best in the world. PEEK offers exceptional performance in a wide range of temperatures and extreme conditions. PEEK combines unique thermal properties with mechanical properties and chemical resistance. PEEK is able to withstand a constant working temperature of 250°C and offers excellent long-term chemical resistance. It is considered one of the best heat-resistant thermoplastic materials.

Strengths :
+ Resistance at high temperatures
+ Resistant to numerous chemicals
+ Excellent mechanical strength, rigidity and hardness at high temperatures
+ Operating temperatures from -40°C to +250°C (for short periods up to +310°C)
+ Flame resistance: UL94 V0


Points faibles :

Applications :
often used in the medical and aerospace sectors, the automotive industry, the electronics industry, etc. and other demanding industries


Information and advice

The majority of our plastic fasteners (washers, spacers, nuts, screws, bushings) are made from raw plastic, which is the most cost-effective solution. This virgin plastic is entirely suitable for technical components whose appearance is not important. As a virgin product, plastic such as nylon will often have a colour on the white spectrum tending towards ivory or may be completely transparent like PC (Polycarbonate or PMMA).

All the material properties of our products appear in our product catalogue, alongside the product descriptions. In any case, we recommend that you perform trials with our plastic parts, of which we will provide free samples. For all specific chemical, mechanical or thermal applications, we are also able to offer you other materials (see our “bespoke products” section). We will be happy to advise you.


Need help ?

Do you need more information, personalised advice or a special request about a current order? Just get in touch with us! Our team of advisers is available Monday to Thursday, 7.30am to 4.30pm and Friday 7.30am to 1.15pm.