Shot blasting is a specialized surface finishing process where small metal (or mineral) pellets, called blast media, are thrown onto the surface of a work piece at incredibly high speeds. With rates of speed ranging from 200-800 feet per second, the impact on the work pieces from this process is what produces the desired surface finishing effect.
The process components of a shot blasting system include a shot blast machine, raw and finished work pieces, blast media, dust, and other byproducts. Rosler has more than 80 years of experience in developing comprehensive shot blasting systems.
The resulting interlinked system meets the most demanding cleanliness specifications while achieving significant cycle time reductions and cost savings and providing a high degree of operational flexibility.
The Situation
Headquartered in Lennestadt, Germany, VIA sought an integrated solution for de-oiling, mass finishing, and deep cleaning of stamped and formed parts.
For nearly a decade, Sales Representative and Interim Product Manager of Turbine Blast Equipment Zack Murray has been one of Rosler’s top shot blasting experts.
Working with customers and our global Customer Experience Centers, he helps develop and test surface finishing machines and media in addition to dialing in specific process parameters.
At times, adhering to the Rosler motto and guiding principle of “finding a better way…” can be difficult and complicated. Luckily, Murray and the entire Rosler team are committed to delivering world-class surface finishing equipment, consumables, and service in a variety of industries.
In this post, Murray shares the most challenging issue he has tackled at Rosler and how the team developed a solution.
One of the first considerations in finishing process development is the ability to effectively separate mass finishing media from the work pieces. If separation cannot be achieved, the process will not be viable. Signs of inadequate separation may include the need for too much manual intervention, lodged media causing downstream process issues, failure to meet finishing standards, or even product recalls.
For processes that do not require work pieces to be firmly mounted to fixtures in the machine, components and media loosely tumble in mass finishing processing bowls and troughs to achieve the desired finishing result. While this interaction is encouraged during processing, swift and precise media separation is crucial before work pieces move onto the next process step.
Rosler has more than 80 years of experience designing mass finishing machines and supplying consumables. Our expertise can help develop the best separation method and settings for your unique combination of finishing, work pieces, and media.
Separation Objectives
If not properly removed from work pieces, media carried out of the machine can cause disastrous results in automated, downstream manufacturing operations such as machining, assembly, painting, etc. The manner in which media and work pieces are separated matters as well.
Growing utilization of additive manufacturing for volume production of plastic components has increased the demand for cost-efficiency and high-quality surface finishes. That’s why AM Solutions, a brand of the Rosler Group, has further expanded its product portfolio with the development of a new media type for post processing of plastic components.
Designed specifically for work pieces printed with MJF and SLS powder-bed-based technology, AM Solutions’ new media permits the safe, cost-efficient finishing of 3D printed components with different shapes and sizes in one single process step and with absolutely repeatable results. This eliminates the time-consuming and costly media changes for different processing stages.
In combination with an understanding of respective printing processes, the new media mix generates a perfect, finely structured, and highly homogeneous surface finish.
The family-owned business located in Kammerstein, Bavaria, works with automotive, machinery building, electronics, medical engineering, jewelry, and a variety of consumer goods customers.
Unlike dry blasting that only uses a solid abrasive media, wet blasting processes use a slurry of water with the shot blasting media. This greatly cushions the impact energy on the work pieces, providing gentler, yet effective results for delicate work pieces. The achieved surface finish and appearance will also differ between wet and dry processes, even when the same media type and size are used.
With more than 80 years of experience worldwide, Rosler can supply both the machines and media best suited for your wet blasting needs.
Common Media Types
As long as it is heavier than water and not water soluble, practically any media used for dry blasting can be used for wet blasting.
It is important to consider the usefulness of the media compared to its cost. While a cheaper or longer-lasting media may be available, it may also require additional processing time to accomplish the desired surface finishing. Selecting the most appropriate media for your process requires balancing initial costs with overall results.
Numerous functions and calibrations factor into developing a precise and stable mass finishing process. From media and compounds to work piece characteristics and processing times, successful finishing requires each process aspect to be carefully monitored and evaluated. When it comes to process water flow rates, poor drainage from the machine can cause quality control issues as well as equipment damage and costly downtime.
While simple in their function, drains play an integral role in regulating the flow of process water out of the machine. With the exception of intentional “flooding” of the process bowl for sharp work pieces, the same amount of compound and water entering the machine must be flushed out again. Otherwise, contaminants in the form of dirt, media, metal fines, and, frequently, oil will accumulate in the process water. Since this buildup can cause the finishing process to deteriorate and even collapse, mass finishing machines must have sufficient drainage!
With more than 80 years of experience, Rosler can expertly design mass finishing technology and troubleshoot issues to protect your system for the life of the machine.
Made from plastic such as polyurethane or stainless steel material, these drains must allow process water and media debris to be flushed from the system while retaining usable media mix and the work pieces.
Media selection is key in any surface finishing process since these consumables are essential “precision tools” required to achieve the specified finishing results.
Whether you are developing a new mass finishing process or changing process parameters including different work pieces, process times, and requirements, partnering with an experienced expert will help you in evaluating all process parameters.
With decades of experience developing mass finishing machines and manufacturing media and compounds, Rosler is an excellent source for guidance. In some cases, pre-tumbled media may be suggested.
What is Pre-tumbled Media?
After production, some types of pre-polishing and polishing media are pre-tumbled by the manufacturer. This process breaks sharp points and corners off individual media pieces to create smoother edges.
“Glazing” occurs when the surface of the media becomes contaminated with metal fines and other debris from the work pieces. As a result, the media becomes very shiny and frequently looks like a piece of aluminum, brass, steel, zinc, etc.
Because glazed media completely loses its original surface properties, it no longer has any grinding effect. Instead, glazed media creates a sort of uncontrolled burnishing. It also retains dirt and other particles which are then deposited on the work pieces.
The image above depicts (from left) media states include clean, heavily glazed, partially cleaned, and fully cleaned.
Rosler has more than 60 years of media production experience. In that time we’ve seen—and corrected—countless examples of ineffective surface finishing as a result of media glazing.
