Productivity in rollforming: comparing different technologies to achieve the best productivity and the best operating results
Many of the companies that contacted us from the profile production sector, made profiles from metal sheet, prepared punched strips and folded them using a bending press.
A great many companies still operate like that and it’s an adequate system when there’s an extremely high variability of pieces, materials and shapes.
However, this processing system generates a huge number of inefficiencies, starting from material waste, then the labor necessary for handling and logistics and ending with the time required for folding.
Taken from the book “The Revolution of Efficiency”
Whether carried out manually or automatically, bending performs one fold at a time on the material and the cycle time for a piece is calculated in minutes and productivity is not scalable: this technology can only increase the number of pieces produced by increasing the number of presses and operators.
However, when there are repetitive products, such as paneling, ventilation profiles, construction profiles, lighting, suspended ceilings, protection from the sun, interior finishing and, in general, when a company has its own OEM product, a different approach to production becomes essential.
Roll forming performs all folding on a profile simultaneously and at over one hundred meters per minute.
The cycle time is calculated in seconds, while all the inefficiencies caused by picking up and depositing, as well as the cost and absorption of cash flow by intermediate warehouses, are eliminated.
Furthermore, this type of line makes it possible to add parametric punching, to obtain profiles that have different punching specifications and are completely finished out of the machine. Also, while using pre-finished materials such as pre-painted or plasticized parts, it’s no longer necessary to paint the pieces in a separate operation.
Below is an account by Frank Dhont, head of industrialization of the Belgian Stow group.
“The Stow group produces logistics and shelving systems and employs 1800 people at its various factories in Europe and elsewhere.
Companies such as Duwic, Lapouyade and Tixit, which were already Dallan customers, joined the group in 2019. At Lapouyade, in particular, we worked with Dallan to create a production system for high capacity shelves (tablettes), featuring a roll forming machine used after our fixed die press.
The problem we had was low productivity and flexibility, since the press required long tooling operations to switch from one format to another.
We wanted a system that would allow the production of 10 panels that were fully punched, stitched and complete with end fold per minute, together with extremely quick product changeover times.
When I visited Dallan the first time, I felt it was important to see the quality of the organization and the technical support. On a project like this, it was important to exploit our experience as manufacturers and the solutions from the systems supplier right from the start. I found Dallan and its technical director Fabrizio Caon possessed great levels of competence and willingness: working as a team, we were able to improve shelving capacity and machine performance, in terms of speed, at the same time.
Instead of the press we started off with, we inserted a multi-servo-electric press, featuring multiple dies and pneumatic actuators, which allowed the production of all formats with a minimal number of operations.
When changing the format, the duplex roll forming machine and the end folding units automatically reposition, making the operation much faster than it was on the previous machine. It should be noted that the system can process metal sheers that range from 0.5 to 0.8mm in thickness. The quality of the panels and folds was excellent.
Stow and Dallan had to work together during the start-up phases and it was important for us to be able to count on a supplier that keeps its word, accompanied by a handshake.”
Subsequently, as we will see, it’s possible to add the packing and packaging modules to obtain the finished, packaged product and it’s also possible to add quality control on the line.
That way, the products are made by a real system that only requires supervision by an operator, where:
- All flows are optimized;
- There’s maximum productivity;
- The margins are multiplied per piece produced.
A simple system is needed to decide which technology is most suitable, based on the quantities of pieces to be produced annually.
In one of the last chapters, I’ll demonstrate how to use simple formulas to calculate how many pieces (N) justify an investment in roll forming equipment compared to bending equipment. I call the number N the discriminant.
The formula I developed is simple and elegant. Here it is below, as a matter of expediency or convenience:
N = 3600 · (cost of roll forming equipment) / [(hourly cost of bending press) · (bending press cycle time)]
We’ll see how to obtain this extraordinary formula and what the values of N are for the different profiles in a specific chapter.
Taken from the book “The Revolution of Efficiency”
CEO – Dallan Spa