Experts at Leitz Tooling help troubleshoot tearing, fuzzing, and blow out on a window production line.

Question: We recently started up an architectural window production line and we’re struggling with tearing, fuzzing, and blow out. Our goal is a high-end product. Fillers and other repairs won’t do.  As a result, we’re scrapping far too many parts.
Consider: There many critical variables to consider when answering this question; tooling, wood species, workpiece clamping, tool-holding method and machining speed, among others.
Start Here: Initially, you can realize improvements by making certain to utilize the proper cutting angle and chip load for the wood species being processed.  Quality improvements can also be achieved by cutting end grain before long grain, and climb cutting instead of conventional cutting.  However, these process steps provide limited improvements in efficiency and productivity.
Where Problems Originate: The most common machining defects are a result of excess cutting pressure.  Scrap loss can be virtually eliminated by reducing the forces required to machine the material.  In general, standard cutting pressure splits natural wood along the grain, resulting in plucking, tearing and the other defects you are experiencing.  
Cross-grain cutting severs wood fibers.  With improper or poorly-maintained tooling, excess cutting pressure often causes blow-out as the cutter exits the workpiece.  Cutting pressure, the amount of force required to efficiently cut material, can be reduced through proper cutting angles, face-shear angles, knife velocity, and chip load.   
Initial Adjustments: In addition to checking your cutting angle, knife shear reduces cutting pressure by changing the cutting dynamic from a chiseling action to slicing.  Knife velocity and chip load are controlled by spindle RPM and feed rates, and should also be set according to wood species-specific chip load charts.  


Heating up CNC productivity

At higher RPMs, a cabinetry firm finds problems with tool holding having a negative impact on accuracy.  Learn how the experts at Leitz Tooling helped.

Tooling Improvements: Innovative tool engineering has paired ripple (Integral) and finish knives.  This positions a pre-cutting knife with ripple serrations directly ahead of the finish knife.  The ripple knife generates very light cutting pressure, preventing pre-splitting of the wood grain.  The finish knife machines away the pre-scored ripples, again under very light cutting pressure.  The pre-cutting and finishing action provided by the paired knives greatly reduces pressure-related defects, and provides outstanding finish quality.
Innovations: Leitz VariPlan Plus Integral planing and ProfilCut Q profiling systems utilize this paired-knife technology to provide premium cut quality with virtually zero scrap.  The close proximity of ripple and finish knives eliminates any problems caused by machine spindle run-out.  The finish quality provided by this system is absolutely perfect, even in knotty and rustic wood species.
Leitz VariPlan Plus Integral planing system
Additionally, the ProfilCut Q Premium series is the fastest cutterhead system in the industry, with speeds 50% higher than competitive tooling, resulting in exceptional productivity in addition to quality results.
Leitz ProfilCutQ Premium profiling system
Results: Manufacturers utilizing ripple/finish technology achieve dramatic reductions in the common defects experienced by wood products producers.  These advances in tool engineering have dramatically enhanced the manufacturing of wood windows, cabinet doors, interior doors, and millwork.  
Learn more about Leitz VariPlan Plus Integral here:  
Learn more about Leitz ProfilCut Q Premium here:
Optimized process efficiency is a moving target, changing with every machine, tool or raw material.  Leitz is committed to ongoing R&D, focusing on continuous acceleration and optimization of machining processes, helping shape the future of customer applications and industries we serve.

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