Product category:
Polishing, buffing and surface texturing
News Release from: Surtech Surface Technology Products | Subject: Robotic wet abrasive grinding/wet polishing
Edited by the Manufacturingtalk Editorial
Team on 14 December 2005
Wet abrasive band grinding applied to
car trim
German robot cell manufacturer has developed a wet abrasive belt grinding (or 'linishing') process for car trim components, which considerably reduces material costs and improves quality
Messrs Cimotec, the leading German manufacturer of robot cells for mechanical finishing have developed a wet abrasive belt grinding process, which considerably reduces material costs and improves consistency and quality The new process gives Western European manufacturers of CAE trim a chance to stay competitive
This article was originally published on Manufacturingtalk on 1 Mar 2004 at 8.00am (UK)
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The car industry has rediscovered the shiny decorative strip as a way of enhancing the visual appeal of new models.
Even small cars are being fitted with one or more decorative strips of aluminium or stainless steel.
With middle and top of the range cars this trend has become even more evident.
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A few years ago shiny decorative strips gave way to the cheaper plastic variety, which no doubt also fitted in with the spirit of the age.
As a result of these measures, manufacturing production capacity for high value polished decorative strips was reduced and demand fell.
Nowadays aluminium decorative strip is in demand once more, and ever bolder designs require new manufacturing techniques and more capacity.
Because of the incalculable element associated with the manufacturing of this high value product, especially where anodizing quality is concerned, outsourcing to countries with lower labour costs is not always successful.
It is necessary, therefore to build up and extend manufacturing capacity at home, even if only on the grounds of the shorter transport routes to the customer and the on-the-spot know-how in the manufacturing of these products.
As a rule a decorative strip consists of a pressed aluminium profile which is bent and mechanically processed.
With the vast majority of strips, a polishing process follows, while in the case of some strips with very pronounced bends, an additional abrasive belt polishing process is necessary to prepare the surface for successful polishing.
This polishing of high-value aluminium profiles is often a tricky process.
The aluminium alloys used for decorative strips are very soft and, after a certain time, the spaces between the abrasive grains on the polishing belts become filled with aluminium deposits.
This effect does not appear as soon with coarse abrasive belts as with finer belts, where the belt is often unusable after only a few parts have been linished.
The life of the abrasive belts is severely reduced while the costs and the problems rise rapidly.
The polishing materials industry has reacted to these problems and has developed a variety of strategies to prevent this effect.
Lubricants, compos and chemical sprays are applied before and during use on the abrasive belts and are intended to prevent clogging of the spaces between the grains.
Some manufacturers of abrasive belts have developed belts with a special coating which is also intended to prevent clogging.
These measures can lead to a significant increase in the life of belts, but the use of this process on robots or CNC controlled machines is not completely satisfactory.
Some years ago, in conjunction with a large polishing company that specialised in aluminium parts for the automotive industry, the old idea of wet polishing was taken up again and implemented in a robot-controlled wet polishing unit.
The idea is simple: water is used to rinse the spaces between the grains of belt.
Water can be applied without any problems in the right amounts and water pressures and volumes can be varied.
The aluminium rubbed off on to the belt is transported by the water into a filter where it is pre-cleaned first in sedimentation tanks.
It is then cleaned to the point where it can be used again.
Naturally, in wet grinding side-effects occur.
These are important to solve: the parts must be dried before being further processed.
The demands placed on work piece pallets and work piece holders are quite different from those during dry polishing.
The cleaning effect is so marked in the case of coarse 80 or 120 grain sanding belts that considerable belt life has been obtained.
Where finer polishing belts are concerned, with grain from 240 to 280, the volume of water used needs to be applied with great precision, otherwise a reduction of the removal action through aquaplaning will result.
Another very welcome side-effect of wet polishing is the cooling of the work pieces by the water.
When aluminium is polished dry, the parts can become very hot depending on the grain used, which can lead to problems later in the anodising bath.
The experience obtained so far, in three-shift operation, has been very positive.
With a few refinements to the wet polishing process and the choice of the correct belts, the process can be regarded as a considerable improvement on current practice for polishing aluminium work pieces.
The increased demand for these high-value work pieces means that robotic wet polishing has a long future ahead of it.
(Note 'linishing' is a registered trade mark of a US company - Ed).
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