hi there
Basically I am refering to those cutter such as cutter used in Die-cutting industry. I want to know how to determine or rather is there a universal std to assess the life span of a cutter.
When we consult the cutter supplier = all they provide us is, it depend on how we used it, the material we are die-cutting, our adjustment etc ...(so many "depend") .
I stuck with coming out a simple way to tell my customer (QA) that what is life span before we need to change new one. They want us to provide data to prove it. If we put a std is 3 mths - I need to provide data. But the difficult part is sometime, after 3 mths - we still find the cutter still can use.
Hope I make it simple to understand.
Thks
Your supplier is right and logically, we can deduce that knife sharpness is dependent upon many factors. In this case, it is dependent on the type of paper you use, the way you fix it and also the way you sharpen it.
My guess is your customer is not trying to be difficult but may have bad experience from your product and that's why they insist on some form of control from your side.
According to suppliers data that I get over here, knives to cut recycled paper may last for 2000 to 3000 cuts or cycle and it goes up to 5000 cuts for knives used to cut pure paper (without any recycle content).
Next question is how do you know when a knife needs sharpening? Its by observation of the cuts it made and its functionality such as getting slightly stuck during a cutting operation.
My suggestion is that you need to have regular inspection (hourly?) when the knife reaches a certain cycle/cut (you can estimate and convert to hours/days) of operation. Example:
For those used to cut paper with recycled content, after 2000 cuts
For those used to cut a mix of papers, after 3000 cuts
For those used to cut pure paper after 4000 cuts.
You will need to check the following for signs that the knife needs sharpening:
• The knife hesitates or stalls while making a cut.
• The sheets are not all cut to the same length (usually the top few sheets are longer than the rest of the sheets - this is sometimes called “draw”).
• Cut marks appear on the cut face of the paper.
• The profile of the cut (side view) is not perpendicular to the table.
• The cut does not appear straight when viewed from the top.
• The knife makes a “rougher” sound as it passes through paper.
• Nicks are visible on the cutting edge of the knife.
Sounds like a lot of work? - not really. Use a checklist!
Regards.