Whether you are recycling plastic goods or handling virgin materials, creating a product free from metal contaminants is a lot more important today than in the past. Trends to thinner walls, tinier hot-runner nozzles, and more costly and sophisticated machinery and tooling mean that even the smallest bit of tramp metal can cause expensive problems.
Processors often tend not to recognize the value of Safety Bomb Detector For Public Places. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right until as soon as 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 fall into the item stream.
For this reason, metal-detection technology is used through the plastics industry to safeguard processing equipment and also to ensure product purity. Metal detectors keep the product under strict surveillance constantly and prevent unnecessary machine downtime and costly maintenance.
Once we talk about “metal detectors,” some processors might think first of magnets. These are generally used effectively prior to 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 may be monitored remotely from a computer. This capability provides a record of how and where frequently contamination takes place 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 – The two main basic varieties of metal detectors:
Single-coil systems – Each time a metallic particle falls from the high-frequency electromagnetic field, an eddy current is induced inside the particle, thereby removing energy from the coil system. Because of this the utmost amplitude of the coil’s vibration decreases. More energy will be supplied to increase the amplitude to maximum level. This disturbance in 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 inexpensive solutions for easy, “down-and-dirty” applications. These systems are simpler to set up, but they cannot make up for products that could be slightly conductive, because of the existence of moisture, acidity, or additives like carbon black.
Balanced-coil systems offer product-effect compensation that suppresses false signals caused by the merchandise. The main benefit is to prevent rejecting perfectly good material. Analog versions need the operator to manually reset the compensation as material moisture content or some other variable changes. Newer digital versions could be preset to self-adjust for various products or a variety of moisture content or any other variables within 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 may cause a detector to emit a false signal and reject good material.
You shouldn’t must sacrifice good material for accurate detection and rejection. Along with product-effect compensation, state-of-the-art Deep Earth Metal Detector offer adjustable sensitivity and positive speed control to reduce the quantity of material lost.
Maximum sensitivity of any detector determines the minimum dimensions of metal particle that it can sense. Smaller particles can slip through, and this factor is crucial to choosing 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, in which the sensitivity is lowest. Steel spheres are used because there is a uniform, defined size, meaning the measurements are repeatable. Also spherical particles are 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 which can be detected with maximum sensitivity. A good rule of thumb to keep in mind is the fact that normal sensitivity is approximately 1% in the diameter in the coil. Based upon the sensing aperture, innovative pbgavn are capable of detecting contaminants no more than .4 mm.
Sensitivity is also associated with the composition and form of the fabric. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and more, they may be most sensitive to ferrous particles. That is because metallic particles are detected by means of eddy currents, and the greater the eddy current the larger 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 the sensitivity of ferrous particles is greater than the second. What’s more, eddy currents from metallic particles are just effective on the surface, so the greater the surface, the larger the sensitivity. This means that flat metallic particles, or particles with irregular shapes, are much easier to detect than spheres.
Another feature offered by Long Distance Metal Detector is called positive speed control. Due to differences in bulk density, metal particles might not travel through 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 to be able 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.
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Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China