Whether you are recycling plastic goods or processing virgin materials, producing a product free from metal contaminants is a lot more important today than ever before. Trends to thinner walls, tinier hot-runner nozzles, and more pricey and complicated machinery and tooling imply that even the smallest bit of tramp metal may cause expensive problems.
Processors often do not recognize the importance of X-Ray Security Screening System. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right up to the second it enters the throat of your own molding or extrusion machine. Contamination can vary from tiny particles worn off by equipment abrasion to entire nuts or bolts loosened by vibrations in processing machines. There’s even the human factor: Inevitably, items like coins, pens, and paper will occasionally belong to the item stream.
For that reason, metal-detection technology is utilized through the entire plastics industry to guard processing equipment as well as ensure product purity. Metal detectors keep the product under strict surveillance all the time preventing unnecessary machine downtime and costly maintenance.
Whenever we talk about “metal detectors,” some processors may think first of magnets. These are used effectively before the metal detector for capturing ferrous metals. Less familiar to many processors are electronic detectors for all sorts of metals. These are generally active devices that actuate a valve or some other device to reject the contaminated material.
What’s more, electronic metal detectors could be monitored remotely from the personal computer. This capability offers a record of how and where frequently contamination happens in your plant. Such valuable data can help you compare the purity of various vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are 2 basic kinds of metal detectors:
Single-coil systems – When a metallic particle falls through the high-frequency electromagnetic field, an eddy current is induced in the particle, thereby removing energy through the coil system. Because of this the highest amplitude of the coil’s vibration decreases. More energy will be supplied to increase the amplitude back to maximum level. This disturbance from the coil’s vibration is detected by the electronic circuit as signaling the existence of a metallic particle.
Balanced-coil system – Single-coil systems provide cost-effective solutions for simple, “down-and-dirty” applications. These systems are simpler to setup, however they cannot make up for products that may be slightly conductive, owing to the actual existence of moisture, acidity, or additives like carbon black.
Balanced-coil systems offer product-effect compensation that suppresses false signals brought on by the item. The advantage is to prevent rejecting perfectly good material. Analog versions require the operator to manually reset the compensation as material moisture content or any other variable changes. Newer digital versions may be preset to self-adjust for many different products or an array of moisture content or some other variables in a product.
Making sense of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must definitely be handled with some care. Excessive vibration from motors, chains, along with other nearby equipment could cause a detector to emit a false signal and reject good material.
You shouldn’t must sacrifice good material for accurate detection and rejection. In addition to product-effect compensation, state-of-the-art Metal Detector Hand Held offer adjustable sensitivity and positive speed control to lower the amount of material lost.
Maximum sensitivity of the detector determines the minimum dimensions of metal particle that it could sense. Smaller particles can slip through, and this factor is crucial to selecting the proper detector for an application. Maximum sensitivity is measured by loading a sample of resin with steel spheres and utilizing the measurement in the middle of the coil, where the sensitivity is lowest. Steel spheres are utilized because these people have a uniform, defined size, meaning that the measurements are repeatable. Also spherical particles are the most difficult to detect because of their relatively low area.
All metal separators are certainly not equally sensitive. True sensitivity depends on the scale of the search coil. Smaller the search coil, the lesser the metallic particle which can be detected with maximum sensitivity. An excellent guideline to bear in mind is the fact normal sensitivity is about 1% of the diameter of the coil. Depending upon the sensing aperture, innovative pbgavn are designed for detecting contaminants as small as .4 mm.
Sensitivity can also be related to the composition and shape of the content. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and more, they are most responsive to ferrous particles. That is because metallic particles are detected by way of eddy currents, and the larger the eddy current the higher the sensitivity. Eddy currents on the surface of ferrous particles are greater than those generated on the surfaces of aluminum, bronze, or copper particles, which means that the sensitivity of ferrous particles is greater than the latter. What’s more, eddy currents from metallic particles are merely effective on the surface, so the larger the surface, the higher the sensitivity. This means that flat metallic particles, or particles with irregular shapes, are much easier to detect than spheres.
Another feature available from Food X Ray Inspection Scanner is called positive speed control. Due to differences in bulk density, metal particles may not travel via a pneumatic conveying line in the same speed as the resin itself. Positive speed control senses the particular conveying speed of the metal contaminants and automatically adjusts the open period of the rejection valve so as to eliminate the metal having a minimum of resin loss.
Junhong Electronic&Technology (Dongguan) Co., Ltd is a professional manufacturer since 2005, specialized in R&D of security detection technology. We have various of products range: Walk through metal detectors, hand held metal detectors, X-ray luggage scanners, X-Ray Body Scanner, Underground Metal Detector, Industrial Metal Detector, Checkweigher, Infrared Body Temperature Detection System; Explosives Detector, Under Vehicle Surveillance Systems; etc.
Office: +86-769-22688609, 22688610, 22688612
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Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China