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. 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. Maintaining the correct ratios throughout the course of the job.Ensuring that your processing equipment is running smoothly.Calibrating to ensure that your feeder can and does deliver the right amount of color.Getting this ratio right demands three things: For example, a particular color may be added at a ratio of 25:1, which is equal to 4% of the total material mix. Colorant (or master-batch) manufacturers provide recommended colorant-to-resin mixing ratios for their products. Theoretically, coloring is a simple process. Deliver the Right Ratio to Color Virgin Material Let’s take a look at each of these problem areas. Calculating and delivering the right ratio of colorant to a virgin/regrind mix.Cleaning up and changing over from one color to another.Delivering the right ratio of colorant to virgin material.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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