We helped the customer solve a structural strength problem, which resulted in a patented machine.
What is embossing?
“Chiseling is a method used in the processing of metal products, in which a chisel is used to finish the surface material being processed by cutting or pressing it into the desired shape. This method is sometimes also referred to as ‘stamping,’ although that term is more commonly used to describe a similar process in the printing industry.” (Wikipedia)
Why doesn’t the pin withstand the pipe being cut?
By the spring of 2020, I had been working at Hefmec for about two years while pursuing my master’s degree. I had already seen many different projects in the automotive industry, the food industry, the heavy machinery industry, and many other sectors. Then, during a client project, I encountered a situation that, at first glance, seemed quite harmless:
The customer was developing a punching machine intended to perform a lateral punch on a tube—a task known in advance to be challenging. This was a new method for which high expectations had been set. However, in practical tests, none of the tested punches withstood the demands of use, and as a result, the machine developed by the customer could not be completed.
Hefmec Takes on the Challenge
We had been providing mechanical design services to this highly innovative client for years. The division of labor was clear: the client has decades of experience in solving problems in their own field, and we have extensive experience in utilizing modern 3D design software. For this reason, we were a natural partner to tackle the challenge that had now arisen. Even in the early stages of the project, all parties had a well-informed hunch about the root cause. As we began to examine the challenge more closely, it became clear that, in addition to being a tricky problem, this might also provide material for a thesis.
Root Cause Analysis: The Challenge of Forces Acting on the Blade
Normally, in milling, the material is cut at a right angle, so the forces acting on the tool are parallel to the cutting edge, and their bending effect is minimal. The customer tested various blades without seeing any significant improvements in the cut quality or blade durability. When piercing the tube laterally, the challenge was the lateral forces acting on the tip of the blade, since the blade’s movement does not occur perpendicular to the surface of the tube. These lateral forces caused severe bending at the blade tip, resulting in the cutter failing after only a few penetration cycles.
Simulation of a Problem Situation and Search for the Optimal Geometry
The blade was designed to reduce the forces acting on it. The blade was modeled during the various stages of the cutting process, and the shape of the cutting edge was examined in relation to the resulting hole. The goal was to shape the blade edge so that chips would be removed by shearing rather than tearing.
Reaching a Solution Through Practical Experiments
- Correct clearances
Determining the correct clearances between the cutter and the workpiece was also taken into account. A smaller clearance produces a better cut, but on the other hand, a larger clearance reduces the forces acting on the blade. The correct clearance, which produced a satisfactory cut, was ultimately determined through practical testing. - Lubrication
Lubrication was also added to the blade to reduce friction. This made it possible to further reduce the force required. - Material
Powdered steel was selected as the material for the final blade, as it offered the ideal combination of toughness and hardness. This was further combined with a suitable surface treatment, which made the blade’s surface sufficiently wear-resistant.
The project resulted in a durable blade that also produced a clean cut. The client was able to file a patent for the machine, and I received high marks for my thesis!
Do you face similar challenges related to machining or other manufacturing processes? Please contact Product Manager Petja Lindström (+358 40 740 4771), and together we’ll develop the tools and methods that work best for you!
