Why does a part move on the bed of my CNC router during the cutting process?

There are several reasons why a part may move on the bed during the cutting process. Here are a few examples:

• Poor vacuum due to the condition of the sacrificial bed. If there are too many previous cut lines, your machine will experience vacuum leakage, resulting in weak hold down.
• Too many open zones. Ideally you will only have zones open over the area of your machine you plan on processing material.
• Material thickness. When you are processing the last few millimeters of the cut line there may be too much radial force on the part. This will invariably drag the part towards the tool, damaging both in the process. If the material is thick (10mm or above) then this will increase the chance of the part moving.
• Swarf or chips. Any debris between your material and the sacrificial bed will create an uneven surface and allow vacuum leakage, reducing your hold down.

-Ged Lodge, AXYZ International