While traveling North America and speaking with plastics processors about cleaning their machines, I often hear that they use regrinds for that purpose.
The most popular reason they give me is that it is “free.” Well, this could not be farther from the truth.
Regrinds bring heavy costs.
1. Most regrinds are generated from cold runners. The energy necessary to make the runners as well as the material cost itself are the first true costs of regrinds.
2. These runners need to be ground up in a grinder. The energy to run said grinder and the labor to manage the regrinds are the second cost.
3. Processing conditions. Poor processing conditions can produce parts that become rejects and these need to be ground up. More energy, material and labor costs are involved with this one.
4. Contamination. Sometimes rejects occur with contamination that gets ground up. This leads to (you guessed it) higher costs all around, not to mention, you're putting contamination back into your feed supply.
5. If said regrinds are not recycled back into the process at the side of the machine, then these grinds will need to be managed. Which leads to more costs.
In conclusion, regrinds are far from free. They are not designed to clean, and very well may cause you more problems and elevate costs.
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