Automotive – Shock Absorber Discs - Surface Finishing Very Thin Parts
An example where achieving a repeatable, high quality surface finish poses a challenge to traditional finishing methods is small and very thin parts produced by stamping or pressing. There are many such items manufactured within the automotive industry and mass finishing them to the ever higher standards required, cost effectively, is essential.
Limitations of Traditional Surface Finishing of Thin Parts
A good example is a shock absorber disc that needs deburring, edge rounding and smoothing. Typically produced by stamping and less than 0.5mm thick, the discs are fragile, they easily bend and can be damaged by conventional vibratory finishing. This usually means lesser forces need to be applied during processing, severely extending cycle times. Where time is money, this is not a satisfactory option.
Another problem comes when separating the thin parts from the processing media, comprising ceramic or plastic chips. Often thin parts will stick together and adhere to the walls of the vibratory tub. Where batch integrity is vital, this can lead to batch contamination if emptying and separation is not a hundred percent effective
Technology Breakthrough Boosts Quality and Speed
Centrifugal disc finishing machines offer faster processing times and more precise control, without the associated issues. However, until recently, they had a limiting design constraint. The rotating disc that provides the motion to the media had a gap between the disc and upper process bowl. Not a problem for larger workpieces, but the gap made an area where thin parts could become trapped.
Enter OTEC Präzisionsfinish and their patented zero gap technology. OTEC CF disc finishing machines deliver intensive centrifugal forces that can be 20 times more effective than vibratory systems in deburring, edge rounding, smoothing and polishing extremely thin parts. Saving even more time, each of these finishes is achieved in a single cycle time. Importantly, the gap precision can be set to just 0.05mm for a dry process or right down to zero for a wet process – completely removing the risk of parts becoming trapped.
Shock absorber discs are surface finished in an OTEC CF machine in a wet process using a ceramic abrasive and zero gap. A water compound mixture is added and removed throughout the cycle time, rinsing out finishing particles and benefiting the efficiency of the process. It also results in a clean and corrosion free surface. Spray nozzles prevent parts remaining in the container and ensures that it is completely emptied at the end of the process, preserving the batch integrity. Automated separation guarantees the shock absorber discs are easily removed from the process media, preventing any risk of batch mixing.
Being programmable, the process parameters can be stored on the CF machine control panel and recalled for precise repeatable batch finishing. With containers sizes up to 50 litres capacity and multiple container systems, it is possible to mass finish shock absorber discs to a consistent high quality standard, without any risks of damage or batch mixing.
Zero gap between rotating disc and process tub is a game changer that makes centrifugal the most repeatable, efficient and cost effective finishing technique for stamped parts like shock absorber discs.