G&H Precision employs the power magnetism in its new Spinner deburring and surface finishing system. A rotating magnetic disc activates small stainless steel pins immersed with the components to be processed in an electrolyte-based solution. The process eliminates the inconsistency of hand deburring, avoids possible damage or marking of components and creates a high order of uniformity to the component surfaces in a single operation.
Steve Hill, G&H Precision's managing director, says the Spinner system is best applied to smaller precision machined parts but can also be effectively used on irregular shaped components such as pressed workpieces or die castings and, depending to machine size, would be able to process parts within a 400 mm cube.
Parts made from non-ferrous metals including aluminium, brass, copper, and titanium, as well as stainless steel, can be deburred and fine finished. The system can also be used with most other steels, certain plastics and precious materials to achieve a bright, smooth finish without any effect on tolerances or damage to delicate areas.
The gentle process will not degrade corners or edges of a component and is ideal for use on external or internal threads, slots, chamfers and intersecting holes. Due to the shape and size of the media, it will not lodge or jam in or around component features.
The Spinner system is based on a rotating magnetic disc mounted under the fixed workholding chamber that is a tank containing the operating media, its liquid and the components being processed. The stainless steel pin media, available in a variety of standard diameters between 0.2 and 1.5 mm and between 1 and 5 mm in length, comprise thousands of small pins hardened to HRc 30 with a polished finish. 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.
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, threading any small components that have a hole on a rigid wire ring, allowing clearance for the pins to enter the bore, makes loading and unloading very fast.
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, including angled pins that create a matt rather than a bright finish.
Author: Celia Cadwallader