Composite coatings for tissue cutting machines

Edited by the Engineeringtalk editorial team Aug 30, 2001

Poeton Industries is coating the blade clamps and blade supports of two highly specialised tissue cutting machines manufactured by Thermo Shandon to prepare tissue samples for histology and research l

Poeton Industries is coating the blade clamps and blade supports of two highly specialised tissue cutting machines manufactured by Thermo Shandon to prepare tissue samples for histology and research laboratories.

The blade clamp and blade support are coated with Poeton's Apticote 460G, a composite coating that combines the protection of low friction polymers with the natural hardness and corrosion resistance of nickel to provide excellent hardness, permanent lubricity and superior wear.

Thermo Shandon designs and manufactures a range of machines to help automate laboratory processes.

Two of the machines, the Microtome and Cryotome, are used to prepare samples for pathologists who analyse tissue to determine diseases.

Tissue is prepared by removing water and impregnating it with wax, which enables it to be thinly sliced, stained to enhance it for certain diseases and mounted on a slide ready for microscopic examination.

Both Thermo Shandon machines are fitted with extremely precise cutting blades that slice samples down to one micron thick.

Tissue specimens move against the blade, which is fixed in position and held rigid with a blade support and blade clamp.

As a Thermo Shandon spokesman explains: "Samples are extremely fragile and, when a number of samples are being cut at the same time, they can join together to form a continuous 'ribbon' as they come off the blade.

To prevent the samples folding or creasing it is essential that they slide easily away from the blade clamp and blade support." The spokesman explains that both components are machined from stainless steel to achieve the extremely high tolerances necessary for the slicing process.

The coating specification therefore demanded a material with a combination of excellent corrosion protection and the low friction properties needed to provide a continuous path for the tissue samples.

"Apticote 460G meets the specification and has an attractive finish that enhances the appearance of the machine." He says, adding: "Poeton has been coating the components for over six years now and we haven't found anything that does it better!" Apticote 460G is one of a family of specialised nickel composite coatings that add value to stainless steel and other ferrous alloys.

Apticote 460 combines the protection of low friction polymers with the natural hardness and corrosion resistance of nickel to provide excellent hardness, permanent lubricity and superior wear, abrasion and chemical resistance.

It also provides the opportunity to substantially reduce material costs by coating low cost materials to meet high performance needs.

For example, parts manufactured from low carbon steel and coated with Apticote 460 can be used to replace more expensive alloy components with no loss of performance.

And costs are further reduced when parts can be machined from more workable and readily available metals.

Apticote 460 is suitable for a wide range of metalic base materials.

It is ideal for complex shapes as it is a very uniform coating; and it can be applied selectively or as an overall surface treatment.

Other medical applications have included moulds for producing plastic joints.

These moulds can be manufactured from low carbon steel and coated with Apticote 460 to replace more expensive alloy moulds with no loss of performance.

And costs are further reduced because moulds can be machined from more workable and readily available metals.

Release agents can also be eliminated.

Apticote 460 has achieved four times the wear resistance of electroless nickel in Tabor Abrasor Tests, outperforms hard chrome in dry running applications and will operate at temperatures from -115C to +260C.

It is USDA and FDA compliant, making it ideal for medical and pharmaceutical applications.

It is also specified extensively in aerospace, hydraulics and pneumatics, automotive, plastics and rubber and paper and packaging applications.