We helped the client solve a problem with the strength of their machine, resulting in a patented machine.
What is make-up?
“Stamping is a process used in the treatment of metal products whereby a stamp is used to finish the surface material to be treated by cutting or pressing it into the desired shape. The process is also sometimes referred to as stamping, but is more commonly used to refer to a similar process used in letterpress printing.”(Wikipedia)
Why does the plug not withstand a pipe cut?
In the spring of 2020, I had been working at Hefmec for about two years while studying for my DI degree. I had already seen many different projects in the automotive industry, food industry, heavy engineering and many other sectors. Then, on a customer project, I was confronted with what at first glance seemed like a very innocuous situation:
The customer had a puncturing machine under development to perform a lateral puncture of a pipe that was already known to be challenging. This was a new method for which high expectations had been set. However, in practical trials, none of the punches tested stood up to the test and, as a result, the machine developed by the customer could not be completed.
Hefmec takes up the challenge
We had been doing mechanical design for this very imaginative client for years. The division of labour was clear: the client has decades of experience in the problem domain of his industry, and we have extensive experience in using modern 3D design software. This made us a natural partner for the challenge that was presented to us. From the very beginning of the project, all parties involved had an educated guess about the root cause. When the challenge was examined in more detail, it became clear that, in addition to the visual puzzle, this could also be the subject of a thesis.
Root cause mapping: the challenge of blade forces
Normally, in a punching operation, the material is cut perpendicularly, so the forces on the tool are parallel to the blade and have little bending effect. The customer tried different blades without any significant improvement in the cut or blade durability. In lateral pipe cutting, the challenge was the lateral forces on the tip of the blade when the blade movement is not perpendicular to the pipe surface. The lateral forces caused the tip of the blade to bend violently, causing the puncher to last only a few punctures before breaking.
Problem simulation and search for optimal geometry
The blade was designed to reduce the forces on the blade. The blade was modelled at different stages of the cutting process and the shape of the cutting edge in relation to the hole created was studied. The aim was to shape the edge of the blade so that the chip is removed by shearing rather than tearing.
Through practical experiments to a solution
- Correct clearances
Determining the correct clearances between the plug and the counterpart was also taken into account. A smaller clearance produces a better cut, but on the other hand, a larger clearance reduces the forces on the blade. The correct clearance, which produced an adequate cut, was finally found through practical experiments. - Lubrication
Lubrication was also added to the blade to reduce friction. This allowed the force required to be further reduced. - Material
Powder steel was chosen as the final blade material, combining toughness and hardness in the best possible way. This was combined with a suitable surface treatment to make the blade surface sufficiently wear-resistant.
The end result of the project was a blade that was durable in use and also produced a good cut. The customer was able to apply for a patent for the machine and I was able to get my thesis on the cover with high marks!
Do you have similar challenges with make-up or other manufacturing techniques? Contact Product Manager Petja Lindström (+358 40 740 4771) and together we will develop the tools and methods that are right for you!
