News | June 17, 2011

G&H Precision Introduces Magnetic Deburring And Polishing


A totally new combination deburring and surface finishing process that utilises a rotating magnetic disc to activate movement of small stainless steel pins immersed with the components to be processed in a liquid is now available through G&H Precision Engineering of Southampton. The process eliminates the tedium and inconsistency of hand deburring, possible damage or marking of components and creates a high order of uniformity to the component surfaces in a single cost-effective operation.

Explains G&H managing director Steve Hill, The SPINner system is best applied to smaller precision machined parts but can also be effectively utilised on irregular shaped components such as pressed workpieces or die castings and according to machine size, would be able to process parts within a 400 mm cube.

Parts made from non-ferrous metals including aluminium, brass, copper, stainless steel and titanium, can be deburred and fine finished however, most steels, certain plastic and precious materials can also be processed without any effect on tolerances or damage to delicate areas and as a result, will achieve a bright, smooth finish.

The gentleness involved in the process means that it will not degrade corners or edges of a component and is ideal for use on external or internal threads, slots, chamfers and intersecting holes and due to the shape and size of the media, it will not lodge or jam in or around features of the component.

The SPINner system is based on a rotating magnetic disc mounted under the fixed workholding chamber which forms a holding tank for the operating media, its liquid and components. The stainless steel pin media comprises thousands of small pins hardened to HRc 30 with a polished finish and is available in a variety of standard diameters between 0.2 mm and 1.5 mm and between 1 mm and 5 mm in length. The size of pin is selected to suit the process, the material and typical features to be deburred and polished. As the magnets are mounted in a circular pattern this creates a field array that moves horizontally from the disc and causes the polarity to constantly change as the disc rotates. Inside the working chamber the change in polarity causes the pins to jump and spin in a circular pattern within the electrolyte based solution and in doing so, rubs against the surface of the components.

The machine can be programmed for deburring when the disc is rotated at a slow speed then reversed and the speed of rotation increased for finishing and polishing. Overall processing times for batches of aluminium and copper parts tend to be between 10 and 15 minutes depending on the finish required. Stainless steels can take between 15 to 25 minutes and iron and steel 20 to 30 minutes. In normal production a strainer is used to separate the components from the media. However, a novel work holding arrangement is to thread any small components which have a hole on a rigid wire ring allowing clearance for the pins to enter the bore which makes loading and unloading very quick.

While the process can be fine-tuned by adjusting rotational speed, magnetic force settings and processing time, custom-made pin media can also be supplied by G&H for specific applications which include angled pins that are able to create a matt rather than bright finish.

There are seven sizes of machine in the range from a bench top HD-716 with a 200 g capacity to the HD-7100 II which has work chamber area of 1,000 mm by 430 mm which is also suitable for longer workpieces and will accept component loads up to 500kg. Power can be either 13 amp of 3-phase to all versions of the SPINner

SOURCE: &H Precision Engineering Limited