Whether you are recycling plastic goods or handling virgin materials, making a product free from metal contaminants is a lot more important today than ever. Trends to thinner walls, tinier hot-runner nozzles, and more expensive and sophisticated machinery and tooling mean that even the smallest piece of tramp metal can cause costly problems.
Processors often tend not to recognize the value of Electric Metal Detector. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right up to as soon as 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 also the human factor: Inevitably, items such as coins, pens, and paper will occasionally fall into the item stream.
For this reason, metal-detection technology is 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 preventing unnecessary machine downtime and costly maintenance.
Once we talk about “metal detectors,” some processors may think first of magnets. These are used effectively prior to 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 other device to reject the contaminated material.
What’s more, electronic metal detectors may be monitored remotely coming from a personal computer. This capability supplies a record of how and where frequently contamination takes place in your plant. Such valuable data can help you compare the purity of different vendors’ resins or diagnose excessive machine wear.
How metal detection works – The two main basic kinds of metal detectors:
Single-coil systems – When a metallic particle falls through the high-frequency electromagnetic field, an eddy current is induced inside the particle, thereby removing energy through the coil system. As a result the utmost amplitude of the coil’s vibration decreases. More energy will then be supplied to improve the amplitude to maximum level. This disturbance in 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 inexpensive solutions for simple, “down-and-dirty” applications. These systems are simpler to set up, but they cannot make up for products that may be slightly conductive, owing to the presence of moisture, acidity, or additives like carbon black.
Balanced-coil systems offer product-effect compensation that suppresses false signals due to the item. The main benefit would be to prevent rejecting perfectly good material. Analog versions need the operator to manually reset the compensation as material moisture content or other variable changes. Newer digital versions could be preset to self-adjust for different products or an array of moisture content or some other variables inside a product.
Making feeling of sensitivity – Electronic metal detectors are high-tech, sensitive devices that must definitely be handled with some 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. As well as product-effect compensation, state-of-the-art Security X Ray Baggage Machine offer adjustable sensitivity and positive speed control to lower the amount of material lost.
Maximum sensitivity of a detector determines the minimum dimensions of metal particle that it may sense. Smaller particles can slip through, which means 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 employed because they have a uniform, defined size, which means that the measurements are repeatable. Also spherical particles would be the hardest to detect due to their relatively low area.
All metal separators are not equally sensitive. True sensitivity depends on the scale of the search coil. The smaller the search coil, the smaller the metallic particle which can be detected with maximum sensitivity. An excellent guideline to bear in mind is that normal sensitivity is all about 1% in the diameter in the coil. Depending upon the sensing aperture, innovative pbgavn are capable of detecting contaminants no more than .4 mm.
Sensitivity is additionally 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, these are most responsive to ferrous particles. That 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 higher 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 just effective on the surface, so the larger the surface, the larger the sensitivity. Because of this flat metallic particles, or particles with irregular shapes, are quicker to detect than spheres.
Another feature offered by Cargo Inspection X-Ray Machine is known as positive speed control. Because of variations in bulk density, metal particles might not travel by way of a pneumatic conveying line in the same speed because the resin itself. Positive speed control senses the particular conveying speed in the metal contaminants and automatically adjusts the open period of the rejection valve in order 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.
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Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China