Whether you are recycling plastic goods or handling virgin materials, creating 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 suggest that even the smallest bit of tramp metal may cause costly problems.
Processors often usually do not recognize the importance of Airport X-Ray Scanner. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right until the moment it enters the throat of your molding or extrusion machine. Contamination can range from tiny particles worn off by equipment abrasion to entire nuts or bolts loosened by vibrations in processing machines. There’s also the human factor: Inevitably, items like coins, pens, and paper will occasionally belong to the merchandise stream.
Because of this, metal-detection technology can be used throughout the plastics industry to safeguard processing equipment as well as ensure product purity. Metal detectors maintain your product under strict surveillance at all times preventing unnecessary machine downtime and costly maintenance.
When we speak of “metal detectors,” some processors may believe first of magnets. They are used effectively prior to the metal detector for capturing ferrous metals. Less familiar to numerous processors are electronic detectors for all types of metals. They are active devices that actuate a valve or any other device to reject the contaminated material.
What’s more, electronic metal detectors can be monitored remotely from a computer. This capability supplies a record of how and where frequently contamination occurs in your plant. Such valuable data will help you compare the purity of various vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are 2 basic varieties of metal detectors:
Single-coil systems – When a metallic particle falls from the high-frequency electromagnetic field, an eddy current is induced within the particle, thereby removing energy from the coil system. As a result the highest amplitude of the coil’s vibration decreases. More energy will then be supplied to increase the amplitude to maximum level. This disturbance from the coil’s vibration is detected by the electronic circuit as signaling the actual existence of a metallic particle.
Balanced-coil system – Single-coil systems provide inexpensive solutions for easy, “down-and-dirty” applications. These systems are simpler to setup, nevertheless they cannot make amends for products that could 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 due to the merchandise. The main benefit would be 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 can be preset to self-adjust for various products or a range of moisture content or other variables within a product.
Making feeling of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must be handled with some care. Excessive vibration from motors, chains, along with other nearby equipment may cause a detector to emit a false signal and reject good material.
You shouldn’t have to sacrifice good material for accurate detection and rejection. In addition to product-effect compensation, state-of-the-art Led Screen Metal Detector offer adjustable sensitivity and positive speed control to reduce the quantity of material lost.
Maximum sensitivity of a detector determines the minimum dimensions of metal particle that it could sense. Smaller particles can slip through, so this factor is essential to deciding on the proper detector for the application. Maximum sensitivity is measured by loading a sample of resin with steel spheres and utilizing the measurement in the center of the coil, where sensitivity is lowest. Steel spheres are employed because there is a uniform, defined size, meaning that the measurements are repeatable. Also spherical particles would be the most difficult to detect because of the relatively low surface area.
All metal separators usually are not equally sensitive. True sensitivity depends on the size of the search coil. The smaller the search coil, smaller the metallic particle which can be detected with maximum sensitivity. An excellent principle to keep in mind is the fact normal sensitivity is all about 1% of the diameter in the coil. Based on the sensing aperture, innovative pbgavn are designed for detecting contaminants as small as .4 mm.
Sensitivity is also related to the composition and shape of the material. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and a lot more, they are most understanding of ferrous particles. This is because metallic particles are detected through eddy currents, and the larger the eddy current the higher the sensitivity. Eddy currents on the surface of ferrous particles are more 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 just effective on the surface, so the greater the surface, the larger the sensitivity. Which means that flat metallic particles, or particles with irregular shapes, are quicker to detect than spheres.
Another feature offered by Walk Through Metal Detector Gate is called positive speed control. Because of differences in bulk density, metal particles may well not travel by way of a pneumatic conveying line in the same speed since the resin itself. Positive speed control senses the specific conveying speed of the metal contaminants and automatically adjusts the open duration of the rejection valve in order to get rid of the metal with 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
MOB/WhatsApp:+86 189 3826 7258
Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China