Whether you are recycling plastic goods or handling virgin materials, producing a product free from metal contaminants is more important today than in the past. Trends to thinner walls, tinier hot-runner nozzles, and more pricey and sophisticated machinery and tooling mean that even the smallest part of tramp metal could cause expensive problems.
Processors often usually do not recognize the value of Portable X-Ray Machine. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right until the moment it enters the throat of your own 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 fall under the merchandise stream.
For this reason, metal-detection technology can be used through the entire plastics industry to safeguard processing equipment as well as ensure product purity. Metal detectors maintain your product under strict surveillance at all times and stop unnecessary machine downtime and costly maintenance.
Whenever we talk about “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 other device to reject the contaminated material.
What’s more, electronic metal detectors could be monitored remotely from the computer. This capability supplies a record of how and where frequently contamination takes place in your plant. Such valuable data may help you compare the purity of different vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are 2 basic varieties of metal detectors:
Single-coil systems – Whenever 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 maximum amplitude from the coil’s vibration decreases. More energy is then supplied to increase the amplitude back to maximum level. This disturbance from the coil’s vibration is detected from the electronic circuit as signaling the actual existence of a metallic particle.
Balanced-coil system – Single-coil systems provide cost-effective solutions for simple, “down-and-dirty” applications. These systems are easier to create, but 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 due to the product. The main benefit is always to prevent rejecting perfectly good material. Analog versions require 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 different products or a variety of moisture content or other variables within a product.
Making sensation of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must be handled with a certain amount of care. Excessive vibration from motors, chains, and other nearby equipment could cause a detector to emit a false signal and reject good material.
You shouldn’t need to sacrifice good material for accurate detection and rejection. Along with product-effect compensation, state-of-the-art Food Checking Weigher offer adjustable sensitivity and positive speed control to minimize the amount of material lost.
Maximum sensitivity of a detector determines the minimum scale of metal particle that it can sense. Smaller particles can slip through, so this factor is crucial to selecting the proper detector to have an application. Maximum sensitivity is measured by loading a sample of resin with steel spheres and using the measurement in the middle of the coil, where sensitivity is lowest. Steel spheres are utilized because these people have a uniform, defined size, meaning that the measurements are repeatable. Also spherical particles would be the hardest to detect because of the relatively low surface area.
All metal separators are not equally sensitive. True sensitivity depends on the size of the search coil. Smaller the search coil, smaller the metallic particle that can be detected with maximum sensitivity. A great principle to bear in mind is the fact normal sensitivity is all about 1% of the diameter of the coil. Based on the sensing aperture, innovative pbgavn are capable of detecting contaminants as small as .4 mm.
Sensitivity is additionally related to the composition and model of the content. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and much more, they are most responsive to ferrous particles. This is because metallic particles are detected through eddy currents, and the higher the eddy current the greater the sensitivity. Eddy currents on the surface of ferrous particles are more than those generated on the surfaces of aluminum, bronze, or copper particles, meaning the sensitivity of ferrous particles is higher than the second. What’s more, eddy currents from metallic particles are merely 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 much better to detect than spheres.
Another feature offered by Checking Weigher Machine is referred to as positive speed control. Due to variations in bulk density, metal particles may well not travel through a pneumatic conveying line on the same speed as the resin itself. Positive speed control senses the actual conveying speed in the metal contaminants and automatically adjusts the open period of the rejection valve to be able to eliminate 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
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Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China