Blasting with balotine to very low roughness

30. 1. 2023

Glass bead blasting is a technique that provides a final surface finish to stainless steel products. Our company has been performing it for more than 20 years to the great satisfaction of our customers. During this time, we have encountered a wide variety of requirements for the final appearance of the blasted product and each such request has pushed us further..

One of the basic parameters of the blasted surface is its shade. Some customers require the lightest possible shade of the resulting surface, while others require the darkest possible shade. Another parameter that is monitored in the process and can be significantly influenced is the resulting surface roughness. High roughness requirements can be met quite easily - just use a coarser abrasive and the resulting roughness will be higher. However, for the lowest possible roughness requirement, it does not work that simply. Many more input factors need to be adjusted, and the technology needs to be adjusted as well. A surface roughness of around Ra = 1.6 µm is commonly achievable. This is used for the vast majority of machines and parts for the food industry.

In mid-2022, a long-term customer approached us asking if we would be able to achieve even lower roughnesses - around Ra = 0.8 µm. The condition was, of course, that we would also be able to maintain a high production capacity for industrial applications. We first approached the manufacturer of our blasting technology to ask if it was possible to blast to this low level of roughness with their technology. We received an affirmative answer and a recommendation to modify some parameters. Unfortunately, the result was not satisfactory. We did manage to reduce the roughness slightly (to about Ra = 1.2 to 1.3 µm), but this value was still insufficient. In addition, the blasting speed and therefore the productivity of the work was very significantly reduced. If we translate this low productivity into a necessarily higher unit price for blasting work was very significantly reduced. If this low productivity were to be translated into a necessarily higher unit price for blasting work, the resulting product would no longer be competitive on the market and thus unsaleable.

We didn't want to admit failure, so we decided to go about it in a completely different way. We ignored the recommendations of blasting technology suppliers and relied on our own experience of over 30 years of blasting stainless steel. To solve this task, we have assigned a team of employees in our company consisting of a technologist, a chief mechanical engineer, a blast shop foreman and several other employees including blast booth operators. Within a few months, despite initial setbacks, we managed to adapt the technology and develop our own know-how so that we are now able to offer our customers balotine blasting with a resulting roughness of Ra = 0.7 to 0.9 µm on an industrial scale and with sufficient capacity. Interest in this service is so high that we have finally permanently allocated one of our four blasting bays primarily for blasting stainless steels to very low roughness.

There are already several other ideas in the minds of our development team to improve the current technology. Thus, we hope to continue to successfully develop and improve this technology to the maximum satisfaction of our customers. We look forward to working with new and existing customers and the challenges they will present us with their new requirements!

Ing. Pavel Kalný - Director