Whether you are recycling plastic goods or processing virgin materials, creating a product free from metal contaminants is a lot more important today than ever. Trends to thinner walls, tinier hot-runner nozzles, and more pricey and complicated machinery and tooling imply that even the smallest part of tramp metal may cause expensive problems.
Processors often tend not to recognize the importance of Walk Through Metal Detector Door. Even virgin material can acquire metal contaminants at various stages of manufacturing and transportation, right until the second it enters the throat of your 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 even the human factor: Inevitably, items including coins, pens, and paper will occasionally fall under the merchandise stream.
For that reason, metal-detection technology can be used throughout the plastics industry to guard processing equipment and to ensure product purity. Metal detectors keep the product under strict surveillance at all times and stop unnecessary machine downtime and costly maintenance.
Whenever we speak of “metal detectors,” some processors may believe first of magnets. These are generally used effectively ahead of 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 other device to reject the contaminated material.
What’s more, electronic metal detectors can be monitored remotely coming from a computer. This capability supplies a record of how and where frequently contamination takes place in your plant. Such valuable data will help you compare the purity of various vendors’ resins or diagnose excessive machine wear.
How metal detection works – There are two basic kinds of metal detectors:
Single-coil systems – When a metallic particle falls from the high-frequency electromagnetic field, an eddy current is induced in the particle, thereby removing energy through the coil system. Because of this the utmost amplitude of the coil’s vibration decreases. More energy will then be supplied to boost the amplitude to maximum level. This disturbance in the coil’s vibration is detected from the electronic circuit as signaling the 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 set up, however they cannot make amends for products that may be slightly conductive, because of the presence of moisture, acidity, or additives like carbon black.
Balanced-coil systems offer product-effect compensation that suppresses false signals caused by the item. The main benefit is always 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 can be preset to self-adjust for various products or an array of moisture content or other variables inside 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, along with other nearby equipment may cause a detector to emit a false signal and reject good material.
You shouldn’t have to sacrifice good material for accurate detection and rejection. Along with product-effect compensation, state-of-the-art Metal Gold Detector offer adjustable sensitivity and positive speed control to minimize the volume of material lost.
Maximum sensitivity of any detector determines the minimum scale of metal particle that it can sense. Smaller particles can slip through, so this factor is essential to choosing 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 midst of the coil, in which the sensitivity is lowest. Steel spheres are used because these people have a uniform, defined size, which means that the measurements are repeatable. Also spherical particles are the most challenging to detect because of the relatively low area.
All metal separators are certainly not equally sensitive. True sensitivity depends on the size of the search coil. The smaller the search coil, the smaller the metallic particle that may be detected with maximum sensitivity. A good rule of thumb to keep in mind is the fact normal sensitivity is all about 1% of the diameter from the coil. Based on the sensing aperture, innovative pbgavn are capable of detecting contaminants as small as .4 mm.
Sensitivity can also be 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 are most sensitive to ferrous particles. This is because metallic particles are detected by way of eddy currents, and the greater the eddy current the larger 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 greater than the latter. What’s more, eddy currents from metallic particles are merely effective on the surface, so the larger the surface, the greater the sensitivity. This means that flat metallic particles, or particles with irregular shapes, are quicker to detect than spheres.
Another feature provided by Digital Food Metal Detector is called positive speed control. As a result of variations in bulk density, metal particles may not travel by way of a pneumatic conveying line on the same speed because the resin itself. Positive speed control senses the specific conveying speed of the metal contaminants and automatically adjusts the open time of the rejection valve so as 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
MOB/WhatsApp:+86 189 3826 7258
Email: [email protected]
Address: No.23, Xintian street, Baizhoubian, Dongcheng district, Dongguan city, China