Cheap Polishing?
Almost every profession has misconceptions that seem perfectly logical to outsiders.
The following article outlines a few of them without attempting to provide a complete list.
- Polishing paste is only a small tool—no more than a single key on a keyboard. If I only had one key, or even just a keyboard, you would not be reading this article now...
Polishing is a time-consuming process whose costs can be significantly reduced when approached correctly, but can also increase substantially if mistakes are made.
What Does Surface Finishing Actually Involve?
- 1. What Happens Before the Polishing Paste?
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• defining the required final result by balancing technical possibilities, budget and customer requirements;
• assessing the initial condition and, wherever possible, planning ahead, as described in detail in my article "Planning Polishing";
• determining the amount of material that needs to be removed (also discussed in the second section of the above article);
• evaluating geometric risks and the material's expected behaviour;
• planning the entire process;
• developing the appropriate polishing technology;
• manufacturing the required tools;
• preparing the surface.
Only after all of this does the polishing paste come into play. Even then, certain steps are repeated throughout the process, such as producing custom-made tools suited to the specific geometry, material and polishing objective.
- 2. Why Can't Manual Polishing Be Compared with CNC Machining?
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• CNC machining is based on fast, accurate and repeatable processes that can be planned and quantified in advance.
• Manual surface finishing, by contrast, has no program and no measurable sequence of operations. It relies on what the trained eye can recognise and what experienced hands can achieve.
Material must be removed step by step in relation to the visible machining marks or defects, while continuously keeping the entire geometry and the complete, carefully planned process in mind. Every stage must support the next one and ultimately contribute to achieving the desired final result.
In manual surface finishing, defects created during the coarse stages cannot be eliminated simply by refining the final finish.
Repeatability is not inherent in the process itself. It can only be achieved if it has already been taken into account during the planning of the entire workflow described above.
- 3. The Impact of Surface Preparation.
- I often receive tools on which surface work has already been carried out, but not in the appropriate way.
In such cases, the work cannot simply be continued. It is first necessary to return the surface to a condition from which the desired result can be achieved safely, resulting in additional work and extra cost.
- • Whether the preparation is carried out by machine or by hand, it largely determines the final result.
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• I discuss machine surface preparation in more detail in the next article, which is linked above.
• With manual preparation, an operation carried out incorrectly or with unsuitable tools results not only in additional time and therefore higher costs, but also
• depending on the geometry, excessively deep scratches, grinding marks or damaged edges may even make it necessary to manufacture a new insert.
• If the surface has been prepared incorrectly, these defects must first be removed before the required finish can be achieved. In many cases, this requires more work than starting from a properly machined surface.
- Defects introduced during surface preparation cannot be removed with finer tools or the final finishing stages. On the contrary, the finer the finished surface becomes, the more visible those defects will be.
• In my experience, this is related to a common misconception: many people believe that the final finishing or "bringing out the shine" requires the greatest skill and attention. In reality, surface preparation is no less demanding, and if it is not carried out correctly, the final polishing will never produce the desired result.
To achieve the desired final result, the effect of every preceding step must be understood in advance and the entire process must be built accordingly. In this respect, it is similar to writing a CNC program—if the roughing operation removes too much material, the finishing pass cannot correct the mistake. The difference is that manual surface finishing is carried out without numbers or software, relying entirely on experience, the trained eye and skilled hands.
- 4. The Tools Required.
- Another common misconception is that polishing requires little more than a few polishing compounds, a machine and some spare time.
Let me briefly outline what is actually required for professional polishing—without claiming to cover every aspect. -
• Although the catalogues of polishing tool manufacturers and suppliers are "only" a few hundred pages long,
• every tool is different, making it impossible to manufacture suitable tools in advance for every individual task.
- In addition to the expertise already described, professional polishing also requires, for example:
- Only after all of this do we arrive at the actual polishing materials, such as:
- And finally, the expertise and experience required to combine and apply all of these tools in the right sequence and in the right way.
• Stands, V-blocks and precision vices
• Machinery suitable for machining cylindrical and rotational components
• Rotary, linear and ultrasonic polishing systems, including electric and/or pneumatic equipment selected for the specific application
• Tool holders capable of working at different angles
• Proper lighting with suitable light intensity and colour temperature
• Magnifiers, microscopes and other surface inspection equipment
• A dedicated working environment (for example, a single metal particle from deburring can ruin an almost finished surface)
• Abrasive stones, abrasive cloths and abrasive papers in a wide range of sizes, materials and hardness grades
• Hand-held and machine accessories designed to hold these abrasives for the specific geometry
• Diamond abrasive tools (hand and machine files, diamond films)
• Flap wheels and other rotary abrasive tools
• Lubricants, cleaning agents and cleaning equipment
• Diamond compounds (for different applications and materials, typically in at least six grades)
• Other polishing compounds
• Emulsions
• Polishing sticks made from wood, plastics, composites and metals, available in various hardnesses, sizes and shapes—from tools for gaps of only a few tenths of a millimetre to those suitable for surfaces spanning several hand widths
• Felt, microfibre materials, papers and cotton polishing media, likewise available in various sizes, shapes and hardnesses
• Hand-held and machine accessories for applying these materials
• Custom-made polishing tools and abrasive heads manufactured individually for every unique geometry
Today, polishing compounds can be purchased with just a few clicks. However, the knowledge, experience and complete set of tools required to achieve the right surface finish are far more complex.
I am pleased to assist you in creating cost-optimised surface finishes tailored to your specific requirements, whether for new tools or repair work,so that surface finishing does not generate avoidable costs,
making it genuinely cost-effective within reasonable limits.