Sheet in PBT FG UD 1220x610 mm blue

PBT FG UD is an unreinforced and food approved polybutylene terephthalate in sheet form. The material combines good mechanical strength with low moisture absorption, stable dimensions and broad chemical resistance. The food approved quality makes the sheet useful in components that have direct contact with food, drink or drinking water, within the rules that apply in the EU and the USA for plastic products in food contact. The surface is smooth and the color runs from natural cream white to light brown depending on the batch.

Mechanically PBT is tough and stiff but not brittle. The material holds its shape and stability well both at room temperature and at raised operating temperature, and the coefficient of friction against steel is low. Wear resistance is good in lightly loaded plain bearings, gear parts and precision mechanics. Compared with polyamide, PBT has much lower moisture absorption, which keeps dimensions and properties almost unchanged in damp environments too. That is a big advantage in food production, where steam cleaning and high humidity are everyday, and in equipment that lives outdoors or in changing temperatures.

The chemical resistance is broad for an engineering plastic in the middle segment. PBT handles weak acids, alkalis, alcohols, oils, fats and most food related cleaning agents. Strong lye and hot steam over longer periods should be avoided, since the ester bond in PBT can break down through hydrolysis at raised temperature in an alkaline environment. For repeated CIP cleaning in hot, alkaline media, PEEK or PPSU suit better. For normal food handling and moderate cleaning temperatures, PBT FG UD works very well and is then one of the most cost effective options.

The sheet is used for gear parts, plain bushings, washers, holders, guide elements, conveyor belt components, gasket supports, valve parts and precision parts in dispenser machines and packaging equipment. The unreinforced quality makes the material forgiving to machine, with good surface finish and fine tolerances even on smaller parts. In electrical applications PBT is well proven thanks to its dielectric properties and low moisture absorption, which makes the sheet useful for insulating holders and contact supports in equipment that lives in damp environments as well. The car industry uses PBT widely in connectors and sensor housings, and that same material knowledge carries over to components in other equipment that has to take moisture and temperature.

Machinability is good. Sharp carbide inserts, moderate feed and good chip clearance give a clean surface finish without melt marks. Use compressed air or a coolant that does not heat up too much. PBT is dimensionally stable during machining and moves less than PA grades in later temperature and moisture cycles. The material can be welded with hot air or ultrasound when needed, but bonding is less straightforward; surface preparation is recommended if glued joints are required and epoxy is often the first choice. Keep in mind that food approved parts require the whole chain from raw material to machined part to be clean and documented, so keep the machining area separate from contaminating materials.

On friction, PBT runs more smoothly than PA when dry and is more forgiving than POM in damp environments. That makes the material practical in conveyor belts, lifting roller components and guides for packaging machines where cleanliness and contact with products matter. The material can be used in series production of small parts where going to PEEK or another high performance plastic would be wasteful, but where PA does not reach because of moisture absorption. Over the service life, PBT FG UD often wins the total cost analysis against both polyamide and unreinforced POM in food applications.

When choosing thickness it is worth remembering that the unreinforced quality sits somewhat below glass filled PBT versions in stiffness and dimensional stability, but it gives cleaner surfaces and better friction behavior. For structural components with higher loads a reinforced quality may suit better, but then you lose the food approved profile and some of the friction properties. Do you need help deciding whether PBT FG UD is the right choice for your component, or whether another PBT quality gives a better balance? Get in touch.