Small errors in measurement or calibration.Feeder behavior (screw, motors, control).While this may “solve” the immediate problem, it could mask other problems, since coloring consistency is also affected by: If it is, but product coloration is insufficient, a tempting “quick fix” would involve adjusting the colorant addition rate upward-from 4% to 5%, for example. The first step in problem-solving is to check and validate the colorant feed rate. Costs for colorant are higher than calculated.Costs for labor are higher than planned, usually due to feeder calibration, or maintenance/job changeover problems.Product is incorrectly or insufficiently colored.So, what might indicate you have a problem with an on-the-machine feeder? Signs of On-The-Machine Color Feeder Problems
Potential Savings with Automatic Calibration Automatic Calibration Saves Time and Money Table I shows how automatic calibration can save time and money. This cell continually registers the loss-in-weight of the colorant hopper and adjusts feed rate accordingly.īy comparing the delivery setting (i.e., grams/sec) in the control with the actual changes in hopper weight during the same period, gravimetric feeders can be essentially self-calibrating and self-regulating. Instead of relying on a fixed-volume auger to deliver a consistent weight, a gravimetric feeder utilizes a load cell. However, until a few years ago, it was prohibitively expensive in the simple feeders commonly used on individual plastics-processing machines. Weight-based gravimetric feeding is a newer method that has been the preferred feeding method for polymer blenders for over 20 years.
And the color machine series#
Calibration is accomplished by cycling the feeder at a particular speed, catching and weighing a series of feed samples, then comparing the sample weights to ensure that the auger is dispensing consistently. Colorant is usually fed by an auger screw, with the feed rate calculated based on the volume of colorant delivered with each turn of the screw. Until relatively recently, most color feeders have been volumetric. The amount of colorant metered out can be controlled in two ways – by volume or by weight.
There are three basic problem areas that occur with coloring at the machine: How Coloring at the Machine WorksĪt-the-machine color addition usually involves a color feeder installed at the base of the material hopper on a processing machine.įollowing installation and calibration, feeders meter colorant through a throat adapter, where it mixes with the mainstream of natural resin before plastication in the barrel of the machine. The Benefits of Coloring at the MachineĬompared with the cost of buying pre-colored resin or installing a large-capacity central blender, coloring at the machine can offer significant cost benefits, including lower material inventory costs and improved process flexibility. With so much value riding on color consistency and quality, it’s important to understand the process of coloring at the machine, typical coloring problems and their solutions, and the impact of coloring on the bottom line. Color is often an integral part of the identification and branding scheme of a product, and may, in some cases, be the determining factor in product selection by the user. Along with correct dimensional and mechanical properties, processors know that good color properties rank among the top factors in customer acceptance of a plastic product.
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