Improved quality and lower costs through automated shot blasting operation

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The lack of flexibility and unsatisfactory powder coating qualities at external job shops induced a Dutch manufacturer of industrial furniture to bring its coating operation in-house. Unlike its competitors the company decided to also do the paint preparation by shot blasting in-house with an automatic shot blasting machine from Rösler. Compared to manual processes the shot blasting cycle times are not only eight times faster, but the automatic solution also produces better qualities at lower costs. This resulted in a significant competitive advantage.

ML Constructie produces small tools and industrial furniture. In addition, the company serves other manufacturers with a laser cutting service for sheet metal, tubes and semi-finished products. In the past industrial furniture was generally sold without any protective coating. However, in recent years customers increasingly demanded the furniture to be painted. Due to the rapidly growing demand for color coated products, the company initially had the shot blasting and powder coating of the furniture done by external job shops. Ben Luizink, co-owner of ML Constructie, reports: „We were not satisfied with the handling of our work by the external job shops. Due to long lead times we could not deliver our products as quickly as we wanted. Moreover, most of the time the coating quality did not meet our specifications. For example, we found residual sand from the sand blasting operation on our products. And the coating thickness was generally insufficient. To better control the blasting and coating operations we created our own in-house coating department.” That’s how a few years ago ML Coating was started. Since then it has grown into a coating company that shot blasts and powder coats its own products and provides blasting and coating services to other companies.

Quick investment in a spinner hanger blast machine
One of the first purchases by the newly created company was a spinner hanger blast machine from Rösler. Mike Luizink remembers: „Pre-condition for achieving a homogeneous, high-quality coating is that the components are thoroughly and precisely shot blasted. Most companies in our area still do this manually. However, right from the beginning we decided to automate the entire shot blasting operation.”

More comfortable working conditions and higher shot blasting qualities
Since manual blast operations are hard and exhausting, it is very difficult to find and keep the people for this kind of work. With the Rösler blast machine the employees must only place the work pieces onto the respective  fixtures and remove them after the blast process. Another significant contribution towards a better working environment was the low noise emission, which is considerably lower than the noise from manual blast rooms. Moreover, the automated shot blast process is eight to ten times faster. While in manual blast rooms media quantities about six kg are dispensed per minute, each of the four blast turbines in the spinner hanger machine throws 150 kg of media at the work pieces every minute. Another benefit is that the spinner hanger blast machine is equipped with two rails in “Y” design. This allows the operator to place work pieces onto the fixture at one rail branch, while the work pieces from the other rail branch are being blasted. Therefore, unproductive idle equipment times are more or less completely eliminated. Last but not least, the overall blast cleaning quality is considerably better. “In the automated shot blast process the blast media is getting into even the tiniest work piece corners. This is nearly impossible with manual shot blasting operations”, comments Ben Luizink and continues: „The Rösler shot blast machine is very tight and emits practically no dust. Since we are coating the work pieces in the same hall, this is a huge benefit.”

Lower media and energy consumption results in significant cost savings
That shorter processing times result in lower costs is quite obvious. However, ML Coating achieved significant cost savings in other areas. „After ten blast cycles the sand used in  manual shot blast operations becomes dust and is, therefore, no longer usable. This produces a lot of waste material,” explains Ben Luizink. „Another drawback of manual blast operations is that the sand remains in tight corners of the work pieces and is, therefore, lost. In automated shot blasting machines the entire quantity of thrown blast media is collected in the bottom and transported to the media cleaning system with special augers. This ensures a much longer usable life of the blast media. An additional advantage is that significantly harder blast media can be used.”
In manual blast rooms the compressed air needed for the blast operation is generated by compressors requiring a high energy input. In the new Rösler shot blast machine the blast media is accelerated by direct-drive electric turbines. Ben Luizink explains: „The turbines require a lot less energy than media acceleration by compressed air.” Another important energy-saving feature in the Rösler machine are the Rösler Gamma G turbines with their curved throwing blades. Because of the curved blade design the blast media leaves the throwing blades at a higher speed without additional energy requirements. This results in a higher impact velocity of the media on the work pieces. The energy consumption can be further reduced by intelligent adjustment of the turbine RPM. For example, delicate components can be blasted at 1,500 RPM, whereas stripping of old paint can take place with 3,000 RPM.

Smooth order processing and trouble-free commissioning
Ben Luizink remarks: „During the entire project we had optimal support from Rösler. Initially, the Rösler engineers helped us to decide which shot blast machine is best for us.” Once the decision had been made, the implementation started. For example, for an optimal placement of the machine in the hall the standard equipment layout had to be modified, and the dust collector had to be relocated. Various preparatory work like the installation of electrical conduits and the pouring of various concrete foundations was done by the customer. After a brief review of this work by Rösler the blast machine was installed and commissioned. „Installation and commissioning were completed within one week. After a short operator and maintenance training we were able to fully utilize the machine,” explains Ben Luizink.

Automated shot blasting provides a competitive advantage
At the moment ML Coating is the only company of its kind in the region that does its shot blasting operation fully automatically. Around 80 % of all work pieces can be processed in the spinner hanger blast machine. The remaining work pieces, for example very large and heavy components are blasted manually. If needed, very delicate components can be pre-treated chemically.
About 50% of the work pieces processed in the automatic Rösler blast machine are components for ML Constructie, whereas the other 50% are prepared for coating jobs for external customers. Overall ML Coating achieves excellent shot blasting results, and the company is highly satisfied with the easy operation of the Rösler machine. „We can easily adjust the shot blast parameters such as throwing speed and blast time. This allows us to create work piece specific programs for the various product groups. At the moment we work with twelve programs, which are more than sufficient for our current shot blasting needs,” concludes Ben Luizink.