PTFE (poly­tet­ra­fluoro­ethyl­ene) is a semi-crys­tal­line mater­i­al with­in the group of thermoplastics.

As PTFE, unlike oth­er ther­mo­plastics, can­not be pro­cessed above its melt­ing tem­per­at­ure, semi-fin­ished products and parts are pro­duced in a sin­ter­ing process.

PTFE fea­tures high chem­ic­al res­ist­ance, out­stand­ing thermal prop­er­ties from 200°C to +260°C, anti-adhes­ive beha­viour and a low coef­fi­cient of fric­tion to name but a few.

Mod­i­fied PTFE dif­fers from reg­u­lar PTFE by a shortened molecu­lar chain and an added co-poly­mer. This fur­ther com­ple­ments the pos­it­ive prop­er­ties of reg­u­lar PTFE.

Com­pounds are mix­tures of a base mater­i­al (reg­u­lar or mod­i­fied PTFE) with addi­tion­al organ­ic and inor­gan­ic aggreg­ates. There is no dis­sol­u­tion or chem­ic­al com­bin­a­tion between these sub­stances. So com­pound­ing res­ults in a homo­gen­eous mix­ture of two or more substances.

The aim of com­pound­ing is to optim­ise the prop­er­ties of the com­pound for spe­cif­ic applic­a­tions com­pared to reg­u­lar or mod­i­fied PTFE. The focus is on rais­ing wear res­ist­ance, lower­ing cold flow under load, redu­cing wear of the coun­ter­part, lower­ing thermal expan­sion, improv­ing thermal con­duct­iv­ity, and enhan­cing detectability. 

Poly­ureth­ane seals fea­ture very high per­form­ance, espe­cially high mech­an­ic­al val­ues, abra­sion res­ist­ance, high flex­ib­il­ity and very good res­ist­ance to ozone and aging. Fur­ther­more, poly­ureth­ane moul­ded parts have very good rebound capa­city and high gas tightness. 

They offer very good fuel res­ist­ance and res­ist­ance to many oils com­monly used in tech­no­logy, espe­cially to oils with high­er aro­mat­ic content.

Poly­ureth­ane seals have a long ser­vice life thanks to good tem­per­at­ure res­ist­ance and excel­lent res­ist­ance to oxy­gen and ozone. Poly­ureth­ane there­fore closes the gap between soft elast­omers and brittle plastics.

UHMW-PE is a semi-crys­tal­line ther­mo­plastic with excel­lent notched impact strength, abra­sion res­ist­ance, and tear strength values.

UHMW-PE is the ideal mater­i­al for use in water. The abra­sion res­ist­ance is five to ten times high­er than for pure PTFE, which is why the mater­i­al is the first choice for applic­a­tions in abras­ive envir­on­ments. The mater­i­al is stable in all hydraul­ic flu­ids and offers high res­ist­ance to acids, bases and aggress­ive media.

It offers lim­ited res­ist­ance to aro­mat­ic and halo­gen­ated hydro­car­bons and strongly oxid­iz­ing acids (e.g. nitric acid, chromic acid).

Poly­am­ides are semi-crys­tal­line ther­mo­plastics clas­si­fied accord­ing to dif­fer­ent types (PA6, PA66, PA12). A dis­tinc­tion is made in the pro­duc­tion of semi-fin­ished products between the extru­sion and monomer cast­ing processes.

With a view to the per­form­ance of the mater­i­al, the extru­sion pro­cess neg­at­ively impacts the mater­i­al prop­er­ties. Shear stresses occur­ring dur­ing pro­duc­tion res­ult in chain breaks in the poly­mer mat­rix. The mater­i­als pro­duced in the monomer cast­ing pro­cess, how­ever, have a high­er level of crys­tallin­ity and there­fore much bet­ter mater­i­al prop­er­ties than the extruded types.

So only cast poly­am­ides are used for IDG mater­i­als. They fea­ture very good impact beha­viour, high mech­an­ic­al damp­ing capa­city, tough­ness, high dimen­sion­al sta­bil­ity, very high wear res­ist­ance, good slide and dry-run­ning prop­er­ties, as well as extremely low water absorp­tion, very good creep rup­ture strength, hydro­lys­is res­ist­ance, and good res­ist­ance to chemicals.

PEEK is a semi-crys­tal­line high-tem­per­at­ure res­ist­ant ther­mo­plastic. It meets the highest require­ments in terms of con­tinu­ous ser­vice tem­per­at­ures up to 260°C, chem­ic­al res­ist­ance to almost all organ­ic and inor­gan­ic chem­ic­als, hydro­lys­is res­ist­ance, slide and wear beha­viour, radi­ation res­ist­ance and fire behaviour. 

This mater­i­al also has very good slid­ing prop­er­ties and dis­plays high wear res­ist­ance, even under high thermal load.

Unstable in the pres­ence of UV radi­ation in com­bin­a­tion with atmo­spher­ic oxy­gen, con­cen­trated nitric acid, con­cen­trated sul­phur­ic acid, acid­ic oxid­iz­ing media, some halo­gen­ated hydro­car­bons and aliphat­ic hydro­car­bons at elev­ated temperatures.

PEEK is used for highly stressed parts in medi­cine, chem­istry, industry, sports, and aerospace. For example, slide bear­ings and slide rings, seals, O rings, sleeves, hous­ings, pis­tons, insu­lat­ors, bob­bins, pump parts, valves.

Poly­im­ide (PI) is an extremely high-per­form­ance, non-melt­ing ther­moset plastic that can with­stand per­man­ent thermal stress as well as extreme mech­an­ic­al stress. 

It is free of plas­ti­cisers, low out­gass­ing, extremely dimen­sion­ally stable and wear res­ist­ant, non-flam­mable and res­ist­ant to many chemicals. 

Poly­im­ide fea­tures high long-term res­ist­ance to both UV and radio­act­ive radiation.

Fab­ric-rein­forced plastics are com­pos­ite mater­i­als made of fab­ric and impreg­nat­ing res­in and pos­sibly addi­tion­al lub­ric­ants. Fab­ric-rein­forced plastics are mainly used as pis­ton or rod guide ele­ments to pre­vent metal­lic con­tact between the com­pon­ents and to absorb trans­verse forces that may occur. 

Depend­ing on the mater­i­al selec­ted, guide ele­ments made of fab­ric-rein­forced plastics fea­ture very high com­press­ive strength, high elasti­city, vibra­tion-damp­ing, good fric­tion­al beha­viour, stick-slip-free move­ment, excep­tion­ally good wear prop­er­ties and good media resistance.