Whether you are recycling plastic goods or handling virgin materials, making 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 part of tramp metal could cause expensive problems.
Processors often usually do not recognize the significance of Security Door Frame Metal Detector. 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 may 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 into the product stream.
For this reason, metal-detection technology can be used throughout the plastics industry to guard processing equipment and to ensure product purity. Metal detectors keep your product under strict surveillance constantly and stop unnecessary machine downtime and costly maintenance.
When we talk about “metal detectors,” some processors may believe first of magnets. These are used effectively prior to the metal detector for capturing ferrous metals. Less familiar to a lot of 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 coming from a computer. This capability provides a record of where and how frequently contamination occurs in your plant. Such valuable data may help you compare the purity of various vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are 2 basic kinds of metal detectors:
Single-coil systems – Each time 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 highest amplitude in the coil’s vibration decreases. More energy will be supplied to boost the amplitude to maximum level. This disturbance in the coil’s vibration is detected by the electronic circuit as signaling the presence of a metallic particle.
Balanced-coil system – Single-coil systems provide inexpensive solutions for simple, “down-and-dirty” applications. These systems are easier to setup, however they cannot compensate for products that may be slightly conductive, due 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 benefit is always 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 different products or a variety of moisture content or other variables within a product.
Making sense 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 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 Needle Inspection Metal Detector offer adjustable sensitivity and positive speed control to lower the quantity of material lost.
Maximum sensitivity of any detector determines the minimum size of metal particle that it can sense. Smaller particles can slip through, and 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 taking the measurement in the midst of the coil, where the sensitivity is lowest. Steel spheres are used because these people have a uniform, defined size, meaning the measurements are repeatable. Also spherical particles are the most challenging to detect because of their relatively low surface.
All metal separators are not equally sensitive. True sensitivity depends on the size of the search coil. Smaller the search coil, the smaller the metallic particle which can be detected with maximum sensitivity. A great rule of thumb to keep in mind is the fact that normal sensitivity is about 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 is also related to the composition and model of the fabric. Although electronic all-metal separators will detect ferrous particles, stainless-steel, lead, aluminum, bronze, tin, and a lot more, they may be most responsive to ferrous particles. This is because metallic particles are detected through eddy currents, and the larger the eddy current the larger 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 greater than the latter. What’s more, eddy currents from metallic particles are merely effective on the surface, so the greater the surface, the greater the sensitivity. Which means that flat metallic particles, or particles with irregular shapes, are much easier to detect than spheres.
Another feature available from Under Vehicle Security Checking Mirror is called positive speed control. Due to variations in bulk density, metal particles might not travel by way of a pneumatic conveying line in the same speed since the resin itself. Positive speed control senses the particular conveying speed from the metal contaminants and automatically adjusts the open duration of the rejection valve to be able to get rid of 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