Whether you are recycling plastic goods or processing 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 expensive and complicated machinery and tooling mean that even the smallest part of tramp metal may cause expensive problems.
Processors often tend not to recognize the significance of Tunnel Size X-Ray Luggage Scanner. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right up to the moment it enters the throat of your 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 also the human factor: Inevitably, items including coins, pens, and paper will occasionally belong to the item stream.
Because of this, metal-detection technology is used through the plastics industry to guard processing equipment as well as ensure product purity. Metal detectors keep the product under strict surveillance constantly and stop unnecessary machine downtime and costly maintenance.
Whenever we talk about “metal detectors,” some processors might think first of magnets. These are used effectively before the metal detector for capturing ferrous metals. Less familiar to numerous processors are electronic detectors for all sorts of metals. These are generally 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 the 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 numerous vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are 2 basic varieties of metal detectors:
Single-coil systems – Each time a metallic particle falls with the high-frequency electromagnetic field, an eddy current is induced within the particle, thereby removing energy from your coil system. As a result the utmost amplitude of the coil’s vibration decreases. More energy will be supplied to improve the amplitude back to maximum level. This disturbance in 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 create, however they cannot make amends for products which 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 caused by the product. The advantage is always to prevent rejecting perfectly good material. Analog versions need 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 different products or a range of moisture content or some other variables inside a product.
Making sensation of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must be handled with some care. Excessive vibration from motors, chains, as well as other nearby equipment may 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. In addition to product-effect compensation, state-of-the-art Underground Mine Detector offer adjustable sensitivity and positive speed control to reduce the amount of material lost.
Maximum sensitivity of a detector determines the minimum size of metal particle that it may sense. Smaller particles can slip through, so this factor is crucial to deciding on the proper detector to have an 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 utilized because these people have a uniform, defined size, meaning that the measurements are repeatable. Also spherical particles are definitely the most challenging to detect due to their relatively low area.
All metal separators usually are not equally sensitive. True sensitivity depends on the dimensions of the search coil. Smaller the search coil, the smaller the metallic particle that can be detected with maximum sensitivity. A great guideline to be aware of is the fact normal sensitivity is approximately 1% from 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 associated with the composition and shape of the fabric. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and much more, these are most sensitive to ferrous particles. This is because metallic particles are detected by way of eddy currents, and the larger the eddy current the greater the sensitivity. Eddy currents on the surface of ferrous particles are greater than those generated on the surfaces of aluminum, bronze, or copper particles, meaning that the sensitivity of ferrous particles is higher than the second. What’s more, eddy currents from metallic particles are only effective on the surface, so the greater the surface, the greater the sensitivity. Because of this flat metallic particles, or particles with irregular shapes, are much better to detect than spheres.
Another feature available from Checking Weigher Machine is called positive speed control. Due to variations in bulk density, metal particles may not travel through a pneumatic conveying line on the same speed as the resin itself. Positive speed control senses the specific conveying speed from the metal contaminants and automatically adjusts the open period of the rejection valve to be able 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