Machine Polishing Directly in the CNC Machine!
Filling systems for the food and pharmaceutical industries are subject to stringent requirements. Deburring specialist Kempf ensured compliance with the strict standards in the production of stainless steel pressure vessel lids at Binder GmbH in Crailsheim by using several specialized ceramic fiber surface brushes. This eliminated the need for extensive manual rework.
Custom Stainless Steel Fabrication for Generations
Custom manufacturing according to customer specifications – with this focus, Binder Apparate und Behälterbau has found its niche as a specialist in stainless steel tanks and today supplies customers in the USA and China with quality made in Crailsheim. Founded in 1976 by Roland Binder, the company initially focused on producing wine storage tanks. The location near the major wine regions around Heilbronn initially favored growth, but seasonal dependency eventually led the company in the 1990s to increasingly specialize in the construction of stainless steel tanks for the pharmaceutical, cosmetics, chemical, and food industries.
Still operated as a family business with now 50 employees, the company today primarily manufactures custom pressure, process, and agitator tanks, WHG tanks, centrifuge housings, as well as stainless steel components and modules for plant construction, and even supplies the largest Covid-19 vaccine manufacturer with buffer vessels for vaccine filling lines. Especially when tanks are used in the food or pharmaceutical industries, very high manufacturing quality is mandatory.
High Quality Requirements for Container Lids
For the production of large stainless steel container closures for pharmaceutical applications, the manufacturing process involved milling them from a stainless steel block. Since the closures feature numerous bores, tapers, and grooves, the initial challenge was to produce these areas completely burr-free. Another critical issue in production was the surface finish of the closures. To prevent the medium from adhering, the surfaces must be mirror-smooth. Because every milling cutter leaves certain marks on the surface, especially in overlapping areas, the previous stainless steel container closures had to be painstakingly finished by hand using various grinding and polishing attachments. This process took about an entire workday per closure lid, depending on size.
Since the stainless steel closures are milled from a solid block, unsightly streaks can sometimes appear in the material, which are undesirable for the subsequent use of the entire tank.
Brush Fibers Made of High-Performance Ceramic
To minimize manual rework, conventional nylon brushes were used for the initial machine machining trials. While the results reduced manual polishing efforts on the surfaces, the desired and required values could not be achieved.
After contacting the deburring specialist Kempf, trials were conducted together with field representative Dominik Wiesner using several types from the portfolio of ceramic fiber brushes made of high-performance ceramic.
The tools with brush fibers made of technical ceramic (Al2O3/aluminum oxide) are especially suitable for machining cases where workpieces require a special surface finish. Successful applications in aerospace and automotive industries have confirmed the properties that surpass those of conventional wire brushes or nylon brushes equipped with ceramic particles.
The so-called “oxide ceramic” possesses, for example, a high hardness (harder than steel) and is therefore ideally suited as a cutting material in metal cutting. Because the ceramic is very hard, yet the fiber rods are flexible enough to adapt to the workpiece surface, the use of ceramic fiber brushes produces a uniform grinding effect. This results in consistent and excellent polishing and grinding characteristics, generating uniform surfaces. Furthermore, no secondary burr forms during machining, and no adhesion occurs due to the self-regenerating effect of the ceramic material. Additionally, this type of ceramic is highly heat-resistant, dimensionally stable, and very wear-resistant during deburring and polishing operations. All these properties ultimately lead to remarkable surface qualities (Ra down to 0.06 µ), which are difficult or impossible to achieve with other tooling solutions in machining processes.
By machine polishing directly in the CNC machine, the surface is processed to eliminate the need for manual re-polishing. The surfaces become mirror-smooth.
#burrfree straight out of the machine
The ceramic tooling solutions from Kempf can be applied to a wide range of machining operations. The consistent goal is to produce burrfree straight out of the machine. This enables tooling solutions that can be integrated into the entire manufacturing process and completely eliminate subsequent deburring or polishing operations. The resulting (cost) benefits are especially significant for high-volume production of series components. However, even for custom-made small batch production, the advantages of fully automated machining, as in this case, are substantial.
When passing over the workpiece edges, they are simultaneously deburred and rounded.
No Manual Polishing Work
With only three ceramic fiber brushes used, manual operations were reduced by approximately 75 percent after the initial trials.
For the mechanical surface machining (polishing the surfaces and deburring the external workpiece edges), the most abrasive version of the ceramic fiber brush type BÜA32-CB40M with a 40 mm diameter and blue ceramic fibers was used. The result after machine polishing the stainless steel surface with this ceramic fiber type was so good that manual and subsequent polishing was no longer necessary.
The milled cones were machined according to their angle using the ceramic mini abrasive fiber type BÜA32-EB06M, also with blue ceramic fibers. This tool is ideal for machining the angled inner surface of the cones, as the contact surface is not flat like with other brushes but angled at approximately 50° (pointed).
Since the cones have different exit angles, the ceramic fiber Wheelbrush was additionally used in certain areas. This tool is primarily used when lateral surfaces need to be polished or deburred. The Wheelbrush, always equipped with red fibers, was specifically developed for deburring and polishing convex external surfaces (e.g., pipes) as well as for deburring external threads.
In combination with all three tooling solutions, Binder GmbH was able to shift almost all production processes for this small series into the machine, standardize the processes, and ensure quality. They exchanged a full seven man-hours of pure polishing work on a workpiece for just two additional machine hours for the complete machining.
Fully polished stainless steel closure lid: The visible brush marks can neither be felt nor measured. The machining marks are purely optical.
Automation Increases Efficiency
Ultimately, Binder GmbH was able to meet all customer requirements for the component using only a few ceramic fiber brushes from Kempf and expand the newly implemented automatic deburring and polishing processes to the production of other components. Since then, the labor-intensive and costly manual grinding and polishing have been eliminated, making the entire production more efficient.