In any production process, the possibility of unexpected events and therefore rejected parts in production is always present. Production managers know this well: disruptions are not exceptions, but a structural element of manufacturing that must be managed consciously and systematically.
To reduce rejected parts in 3D laser cutting, action can be taken on several levels: prevention, monitoring, rapid response, and continuous learning. Being able to simplify, through technology, the process that minimizes these unexpected events is one of the keys to optimizing production.
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The problem of rejected parts in 3D laser cutting
In the laser cutting of three-dimensional parts such as stamped, deep-drawn, die-cast metal components, bent or hydroformed tubes, the generation of rejected parts is a particularly critical issue, as it involves very high costs in terms of both material and production time.
In general, for the same material, a three-dimensional part (hot- or cold-formed) costs significantly more than a straight tube or a flat sheet, precisely because it includes processing operations typically performed on dedicated machines equipped with specific tooling tailored to the part geometry.
The chart below provides an indicative overview of the costs of different metal products that can be processed in a 3D laser cutting cell.
The chart provides an indicative estimate of the €/kg costs of various metal products processed by laser.
From the chart, it can be seen that for steel components, the cost of stamped parts can be more than four times that of flat sheet, while aluminum, die-cast parts can cost up to seven times more than the same material in sheet form.
A significant cost increase can also be observed for tubes, moving from straight bars to bent and hydroformed tubes.
However, the issue is not limited to material costs alone but also affects lead times. Die-cast, hydroformed, cold-stamped, and bent parts are produced on dedicated machines requiring specific tooling. Recovering a replacement part, whether from a supplier or another production department, takes considerable time and may result in additional, unplanned processing costs.
These include machine downtime for retooling and delays to other production activities. In this context, a production management MES that synchronizes office and shop floor can make a significant difference.
This situation becomes even more critical when production volumes are low, when every single component is essential, or when dealing with very high-value parts, for which producing rejected parts represents unacceptable waste.
3D laser cutting of a bent tube.
Interruptions in 3D laser cutting and how to prevent rejected parts
During 3D laser cutting, various unexpected events can interrupt production. For example, assist gas may run out, or the cutting area may be contaminated with grease or dust, or covered with adhesive, each of these being a possible cause of laser cut loss.
In cold-formed parts, interruptions may also be caused by offcuts, which release internal stresses during cutting and deform, coming into contact with the capacitive sensor of the laser head.
In all these situations, the processing of the part is interrupted and the part may be rejected.
To avoid this outcome, it is essential to be able to restart production exactly from the point at which the unexpected event occurred. For example, if a series of holes is being cut and the machine stops halfway through one of them, the operator can simply instruct the machine to move back one or two positions and resume cutting.
In this way, the part can be completed correctly, avoiding errors and, above all, preventing the creation of rejected parts.
3D laser cutting of a stamped part for the automotive industry.
How the restart function works in BLM GROUP 3D laser cutting cells
To meet this need, BLM GROUP has developed a dedicated restart function that is simple and intuitive, allowing any operator to manage it directly from the LT-FREE machine interface. This is Active Restart, one of the Active Tools features for 3D laser cutting, which enables production to resume from the exact point where it was interrupted or, if necessary, from an earlier stage.
The video below explains in detail how Active Restart works and its benefits.
Conclusions
In a manufacturing environment characterized by increasingly smaller batches, highly specialized and complex parts, and rising material costs, managing unexpected events and reducing rejected parts is essential to protecting profit margins.
With Active Restart, BLM GROUP’s 3D laser cutting cells help manufacturers resume cutting exactly where it stopped, minimizing rejected parts. A technology designed to move ever closer to the goal of zero rejected parts and maximum efficiency.
