OPTIMISING CROSSCUTS

What sort of accuracy do I need ?
0.2-0.5mm or 1-2mm

This is the first question we need to ask, as generally Optimising Crosscuts are separated into 2 categories:

•    Pushfeed
•    Throughfeed

PUSHFEED OC’s are normally driven by a Linear Encoder, are slower but more accurate. The action is executed by a pusher bar on a long infeed table, which by design, accelerates and slows down in such a way as not to overshoot. These machines tend to be less expensive and aimed at the smaller furniture shops. Price is largely dependent on the required functionality and the maximum infeed length.

THROUGHFEED OC’s are normally roll-fed and operate at very high speeds. This makes them less accurate but able to process large volumes.

The next question to ask is what do I want to achieve with my OC ?
There are 2 basic considerations here:

•    Plain Crosscutting to Optimal size
•    Defect Removal and Optimising

If timber boards are already defect-free, or the application requires only crosscutting to the optimal size to minimize waste, then Defect-Removal is not needed.

Ten + Reasons for Dressing/Planing Blanks for Fingerjointing:

 

  1. The FJ line can be accurately set for width and thickness,

eliminating blockages and re-set downtime.

  1. Already sized blanks means QC can focus on defects
  2. Better efficiency and improved safety in the clamping stations of the FJ
  3. Less friction between boards means efficient jogging and squaring
  4. Cleaner straighter surfaces improve handling and reduce wear on conveyor belts
  5. Cupped twisted and bowed blanks can cause rocking while passing the finger shaping too and can result in expensive blade breakages
  6. Better surfaces will result in accurate fingers resulting in improved alignment further down the FJ press. This means straighter boards with minimized planer straightening and stock         removal downstream.
  7. Bad fingers on skew blanks means poor glue application and glue-linefailure
  8. The press has fences vertical and horizontal, to control the progress of the jointed ribbon through the machine. Variations I   n blank width and thickness causes blockages which take time to free.
  9. Example: you have a joined board 13m long but one blank is 10% under width. To get a clear board you need to convert 10% of the entire board to sawdust.
  10. Less planing after jointing, less stock removal, faster throughput, higher recovery.

 

I can go on and on. Please size your blanks.