Considering wear always needs an analysis of the conditions such as character of wearing element, character of the wear-media and the surrounding conditions. - Obviously, in your case either the wear media, which the screws move is much harder than the screw, or the surrounding conditions have serious influence on wear such as corrosion (seawater) or heat. - Which is the media and the size of the particles and the surrounding conditions ? Do you know the chemical composition of the base material ? Then we have the right hardfacing product for tremendously increasing the lifetime of the screws depending on your budgets. Please reply to manfred@m-wiegel.com. ■

Knowing what material is being conveyed in your application is critical to designing an abrasion resistant long term solution for this problem.

We have many screw conveyors in service with abrasion resistant linings on the flight faces ,edges and barrels that have greatly extended the life of this equipment.

We can also provide linings for the conveyor troughs when this becomes a wear issue.

Please contact us at 724-229-1180 for references and a solution.

Regards,

Don Halulko

VP Sales

halulko@cbpengineering.com ■

Dear Sir

The Reiloy Metall GmbH is supplier of Bimetallic Barrels and flight armoured Screws for the most OEM’s of Injection moulding machines and extruders in the plastic industry.

The resins, which are used in these machines, have additives (glass-fibre, flame retardants etc.) which cause extreme high abrasive and corrosive wear in barrels and on the screws.

Due to this fact we armour the barrel id. By a centrifugal casting process with hard facing alloys.

The layer thickness of this armouring is 1,5 mm and the hardness is approx 66. -58 HRc.

By a PTA welding process we amour the flights of the screws with similar alloys.

I think that we can supply you a solution, but we need more information about the problems.

I would appreciate if you can call me ore send me an Email with more information.

Reiloy Metall GmbH

ppa. Bernhard Bolz

(sales manager)

Tel.: +49 / 2241 / 481 701

Fax.: +49 / 2241 / 403 651

Mobil. + 49 / 151 / 125 23 0 32

E-Mail: Bernhard.Bolz@Reiloy.com ■

Packing of the clearance layer between screw flights and the casing may cause excessive tip wear on the flights. This is likely to occur with fine, damp abrasive products or materials that may 'cake' or fuse to a hard compact.

There are various methods of addressing this phenomenon, which may differ for screw feeders and screw conveyors. Coating the casing barrel is not one, neither is making the flights thicker as this aggravates the power loss and may cause other problems. The indiscriminate application of hard coating to the screws can also raise problems, so the approach should properly reflect the application features.

The first task is to ensure that the screw flights have the most suitable geometric form to resist build-up and minimise the radial pressure. The mechanics of a feeder screw essentially imparts helical motion to the entrained contents and the path is related to the surface finish and geometry of the screw. In general, a ribbon flight offers a more favourable motion than a full bladed flight and is better resistant to clogging and logging, both of which are hazards of handling damp and cohesive products and both severely increase the danger of hard packing the residue layer. Ajax Equipment has developed a special 'Lynflow' form of ribbon flighting for this type of application.

The answer is therefore to review the overall feeder design, taking account of the material, feed rate, inlet length, minimising hopper overpressures whilst guaranteeing reliable flow, considering the inlet length and subsequent conveying length and whether volumetric relief can be offered in the confined conditions.

Then, assuming that other steps may be taken separately, the optimum flight design can be established for the appropriate regions and the construction, with suitable shape and material according to the duty. These features distinguish the specialist from standard equipment manufacturers. I would be pleased to put forward a proposal for a screw to suit the duty via lyn@ajax.co.uk, but regrettably have to draw the line at advising all my competitors the details of our professional experience and techniques.

Lyn Bates ■

you should heed lyns advice entirely-everything we do or in this business has its opportunity cost.

You lose effieciency due to material wear during the transfer process and that is going to happen no matter what.

That is the opportunity cost of your production process, perhaps you should look at emptying the screw or screws at the end of an operating shift to clear any lodged material when ever the process as ends to help reduce wear on components. ■

Dear Sirs,

as a producer of technical ceramics wear protection is one of our most important product areas. Therefore we look back on a wide field of experience concerning wear resistant solutions, where screw feeders are part of.

Wear resistant lining made of alotec ceramics could be a suitable solution for your problems. To make sure to provide the right solution meeting your demands, we would ask you to forward more detailed information to us concerning the dimension, kind of material, temperature, a.s.o.

We look forward to your reply.

kind regards ■