Material guide
PBT, polybutylene terephthalate
PBT is an engineering polyester that holds its dimensions even when things get damp. Stiff, dimensionally stable and with good sliding properties, a steady workhorse for mechanical parts that have to sit exactly right. The closest relative is PET, but with faster machining.
What it is
PBT, polybutylene terephthalate, is a thermoplastic polyester. It belongs to the same family as PET and shares much of its character: high stiffness, good dimensional stability and low moisture absorption. Where nylon swells in a wet environment, PBT stays put, and that is often the whole point of choosing the material. The surface is hard and smooth, which gives good sliding properties and reasonable abrasion resistance. PBT is one of the materials we at PlastShop carry in a narrower range, so get in touch early if you are planning a production run.
Properties
Good dimensional stability, the dimensions hold even in moisture
Hard, smooth surface with good sliding properties
Absorbs less moisture than nylon in a wet environment
Stiff and dimensionally stable, carries load without creeping much
Easy to machine on a lathe and a mill
Good electrical insulation properties
Common applications
PBT goes into mechanical and electrical parts where the dimensions have to be right and moisture must not get in the way. Typical uses are sliding elements, guides, insulators and precision parts in electrical and process environments. When a designer wants the dimensional stability of a polyester but a surface that is easy to machine, the choice often lands on PBT rather than PET.
Limitations
PBT is not a high temperature plastic, and it does not take hot environments the way a fluoropolymer or PEEK does. Resistance to strong acids and bases is limited, so PVDF or PTFE suit aggressive chemistry better. Like most polyesters, PBT is sensitive to hot water and steam over time (hydrolysis), which is worth keeping in mind in a wet and warm environment. Bonding is awkward on the smooth surface, so count on mechanical fasteners.
Our PBT grades take 110 °C in continuous service and 200 °C for short periods, and the material melts at 224 °C.
Grades and variants
We carry PBT in its base version, typically in natural or black. The range is narrow, so get in touch early if you are planning a production run.
Base grades
- PBT natural, base version for mechanical and electrical parts.
- PBT black, the same base version in black.
Additives and reinforcements
- Glass fiber reinforced, for higher stiffness and a higher heat deflection temperature, can be brought in on request.
Filled and reinforced grades are brought in on request, so get in touch with your requirements.
Machining
PBT saws, mills, drills and turns without trouble, and holds its dimensions well afterwards. Keep it away from hot water and steam over time; the material breaks down in that environment.
Formats we can supply
We carry PBT as sheet and round rod. Formats and dimensions are shown in the range. Want a piece cut to size? Enter the dimensions in VisualCutter and you see the price right away.