CNC Plasma/Flame Cutting

Description

I plan on creating a generic CNC cutting table that will be suitable for both Plasma cutting of thinner parts (1mm - 12mm) and Flame cutting of thicker material (13 - 50mm).  The CNC control of this machine will greatly expand the cutting capability far beyond manual cuts with fixtures and patterns.  

 

The problem

Cutting precise patterns and designs is not really possible to the level of precision required without CNC control.  I have a wide variety of materials that I need to have cut for various projects.  Unfortunately these cutting jobs must be out-sourced.  This leads to high costs and long lead times.  It is also very difficult during a design/prototyping phase to get the first iteration perfect.  This can also lead to multiple trips back to the laser shop and additional costs.

CNC plasma tables can be purchased for a relatively reasonable price.  However small shop plasma cutters tend to have a maximum thickness of about 12mm.  This is usually due to the higher price of industrial grade plasma cutters and limitations in available power.  The cost of a CNC plasma cutter that will have a the work envelope I want with the power to cut the thickness I require is quite expensive.

 

My Approach

My goal is to combine both a plasma torch and an oxy/acetylene torch in the same CNC cutter.  This will give me the ability to cut thinner materials at a fairly high rate with the plasme torch or thick materials with the CNC flame torch.

The features I want to build into the CNC cutter are...

  • 80Amp plasma torch
  • oxy/acetylene cutting torch
  • linear guide bearings for the gantry
  • Low price industrial grade CNC controller
  • water table to absorb sparks and spray
  • Capacity to hold a complete 4' x 8' sheet

The design so far allows for easy assembly and shipping on a standard sized pallet.  The water table will function with compressed air to allow rapid draining and refilling for part retrieval.  The axes will be belt driven with appropriately sized stepper motors for fast rapids and accurate cuts.  High loads are not required for moving the gantry and cutting head so using stepper motors is a viable choice in the final design. 

 

Summary and further work

With purchased plasma tables costing over $10K, this project will be a nice addition to the shop at a substantially lower price.  With the entire table build from individul sections, assembly and shipping will be greatly simplified too.  Finally, having the flame cutting feature integrated into the design will increase the variety of material thickness that I can cut.  Having the ability to cut these parts myself will also help to lower the cost of many other projects.