Service Overview

Hallam offers a comprehensive powder coating service with a wide range of finishes including high gloss, metallic, textures and bespoke colours. Hallam can also create finishes with special characteristics (e.g. antibacterial coatings) on ferrous and non-ferrous metallic items, and special plastics and fibreboards ranging in area from a few square millimetres to several square metres. Hallam first installed computer-controlled industrial coating plant in January 2008 and facilities now include a multi-stage cleaning and pre-treatment unit and a fully automatic coating booth.

Powder Coating

Hallam’s powder coating facilities

Hallam’s powder coating plant benefits from the company’s manufacturing expertise in many ways. For example, the special carousels and housings needed to suspend components through the plant are designed and manufactured in-house. Hallam’s resources are also deployed in ensuring that the plant is maintained in excellent condition and that rigorous quality checks are applied.

Hallam also adopts a leading edge approach in applying other protective and decorative surface finishing treatments to metallic components or products through the powder coatings service. These treatments include anodising and plating together with other novel electrophoretic processes.

Powder coated products

Powder coatings produce high specification finish which is consistent, hard, abrasion resistant (depending on the specification) and tough. The choice of colours, finishes and characteristics (e.g. antibacterial powders) is vast, as special powders can be produced by the powder manufacturer. Du Pont and AkzoNobel also produce a wide standard range of textures, colours (including “flecked” finishes”) and gloss levels.

Preparation of castings, extrusions and machined parts in the powder coatings process

The basis of any good powder coating is preparation. The vast majority of powder coating failures can be traced to a lack of a suitable preparation. The preparation treatment is different for different materials. In general, for all applications the preparation treatment for aluminium is as follows: Clean, Rinse, Etch, Rinse, Phosphate, Rinse.

Oils and greases are removed in weak alkali or neutral detergent solutions and the surface is etched to remove heavy oxides. After rinsing, the aluminium is dipped into a phosphate solution to form a conversion coating on the aluminium. This film is chemically attached to the aluminium. After rinsing the aluminium is finally rinsed in demineralized water.

The powder coatings powder is applied with an electrostatic spray gun to a part that is at earth (or ground) potential. Before the powder is sent to the gun it is fluidized to separate the individual grains of powder and so improve the electrostatic charge that can be applied to the powder and ensure the powder flows more easily to the gun.

Because the powder coating particles are electrostatically charged, the powder wraps around to the back of the part as it passes by towards the air offtake system. By collecting the powder, which passes by the job, and filtering it, the efficiency of the powder coatings process can be increased to 95% material usage. The powder will remain attached to the part as long as some of the electrostatic charge remains. To obtain the final solid, tough, abrasion resistant powder coating, the powder coated items are placed in an oven and heated to temperatures that range from 160 to 210 °C (depending on the powder). Under the influence of heat, a thermosetting powder goes through 4 stages to full cure.