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Reasons to Keep Entry Cutting Points on Scrap Material Not Workpiece

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🔍 What exactly are we avoiding by “preventing entry-point burrs”?

 

In both laser cutting and wire EDM, the piercing/start point is where process marks are most noticeable:

  • Laser cutting: The initial piercing point can leave slight burn craters, oxidation spots, or tiny slag and burrs caused by unstable energy during startup.
  • Wire EDM: Near the wire entry hole, start marks, fine cut lines, or even minor material deformation from stress release can occur.
If we start cutting directly on the part itself, these burrs, craters, and cut lines would remain on the finished profile. They’re hard to remove later, and they can affect assembly, appearance, and dimensional accuracy.
Laser Cutting & Wire EDM
🧩 What you described as “cutting the scrap first, then keeping the part” is exactly the industry-standard “scrap-side entry” process.

 

In simple terms:

  1. Place the piercing/start point in the scrap material, not on the finished part.
  2. Begin cutting from the scrap area, tracing the full profile of the part.
  3. Finally, separate the part from the scrap.
This way, all burrs, craters, and burn marks from the start point stay on the scrap. The part’s profile ends up with a “flawless, clean edge” that requires no secondary deburring or finishing.
💡 Beyond just avoiding burrs, this method also solves these issues:
 
 
 
Issue Process Benefit
Start-point burrs / craters Marks are transferred to the scrap, leaving defect-free edges on the part
Stress-induced deformation The scrap absorbs initial stress, so the part cuts more stably with no dimensional shift
Cut lines / joint marks The start point is outside the part profile, eliminating visible lines on the finished edge
Surface oxidation / discoloration Burn marks remain on the scrap, preserving the part’s surface finish
✨ The part in photo is a perfect example of this application.

 

Every piercing point for the holes and outer profiles is intentionally placed in the scrap area outside the part’s boundary. This fully protects the critical edges of the finished part, ensuring:

  • No burrs or craters on part edges
  • Direct assembly-ready condition with no secondary grinding
  • Full compliance with dimensional tolerance and surface finish requirements

Why We Cut From the Scrap Side (Beyond Just Avoiding Burrs)

Starting laser and wire EDM cuts in the scrap material, rather than directly on the finished part, is a precision manufacturing best practice that solves multiple critical challenges at once.
  1. Prevent Part Shift & Machine Collisions

     

    Cutting the scrap area first keeps the workpiece firmly secured to the plate until the very end. This eliminates the risk of parts dropping, shifting, or jamming under the nozzle, which can damage the machine, ruin the part, and cause costly downtime.

  2. Control Material Stress & Minimize Deformation

     

    Metal plates contain internal residual stresses. By cutting the scrap material first, we allow these stresses to release gradually in the waste zone. This ensures that when we cut the final part profile, the material is stable, preventing warping, dimensional shrinkage, and out-of-tolerance errors.

  3. Eliminate Stress Concentration & Prevent Cracking

     

    The piercing/start point creates a localized zone of thermal or electrical stress. Placing this point in the scrap transfers the stress riser away from the finished part. This prevents micro-cracks, chipping, or premature failure, especially on sharp corners, thin walls, and high-stress components.

  4. Guarantee a Flawless, Assembly-Ready Edge

     

    Piercing marks, oxidation discoloration, and initial cut imperfections are all confined to the scrap. The final edge of your part is formed by a continuous, stable cut, resulting in a clean, burr-free surface that requires no secondary deburring or polishing.

  5. Protect Critical Dimensions & Fit Surfaces

     

    Even a tiny indentation or burr at the start point can disrupt mating clearances, alignment, or sealing surfaces. By avoiding these marks on the part profile, we ensure every edge meets its dimensional tolerance and functional requirements, so your parts fit perfectly on the first try.

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