Ferro (PTCR) Process Temperature Control Rings

Ferro (PTCR) Process Temperature Control Rings

In ceramic product production, precise and effective temperature measurement is required, but most measurements are limited in time and space. For example, thermocouples cannot measure the temperature of the product itself, but the ambient temperature of the product. In addition, they can only measure radiant heat, not conductive heat from kiln furniture. PTCR high-precision ceramic firing temperature indicators are used to record the real firing process of fired products (including radiant heat and conductive heat), and are suitable for non-continuous kilns and continuous tunnel kilns, as well as atmospheres such as oxygen, nitrogen, air, vacuum and reduction.

1. Functions of Temperature Measurement Rings

The performance of electronic ceramic products depends on the formula, and the firing process is the most critical. The comprehensive thermal effect of ceramic firing roughly includes: firing temperature, holding time and kiln atmosphere. Various kilns are used in industrial product production and practical research, such as box furnaces, tube furnaces, vertical kilns, tunnel kilns, bell kilns, roller kilns, etc. Electronic ceramics, magnetic materials and powder metallurgy heat treatment all require precise and effective temperature control. However, most temperature measurement methods (such as thermocouples, pyrometric cones, photometers, etc.) are limited in time and space. In actual use, they can only measure the ambient temperature of the product, but it is difficult to measure the cumulative thermal effect of the product itself from conductive heat and radiant heat from different directions and different holding times. In fact, the comprehensive thermal effect in ceramic product production will directly affect the firing quality of the product. The use of temperature measurement rings can not only solve the limitations of time and space, but also measure the radiant heat and conductive heat of the kiln and the comprehensive thermal effect of the entire firing process of the product.

2. Introduction to Ferro PCTR Temperature Measurement Rings 850~1750℃ Ceramic Temperature Measurement Rings

Many high-temperature refractory products need accurate and effective measurement of kiln temperature during production, but most measurement methods and tools are limited in time and space. For example: thermocouples cannot measure the temperature of the product itself, but the ambient temperature during product firing. The thermocouple records the temperature obtained at the top, which is only a point in space and time, and a thermocouple cannot determine the heating process; a single thermocouple cannot provide information on whether the heating in different directions of the kiln is uniform, and it can only measure radiant heat, not conductive heat from kiln furniture.
FERRO PTCR ceramic temperature measurement rings are high-precision ceramic temperature indicators that faithfully record the thermal process experienced by products during firing.
FERRO PTCR ceramic temperature measurement rings can not only measure radiant heat and emissive heat, but also take into account the influence of temperature over time.
FERRO PTCR ceramic temperature measurement rings can conveniently express the heating process with a simple number - Ring Temperature (RT), which is easy to apply in practical work. Temperature measurement rings are widely used in continuous kilns, non-continuous tunnel kilns, shuttle kilns, roller kilns, bell kilns, etc. It is recommended to use multi-position and multi-level placement, which can give you the most direct understanding of the heat distribution in the kiln. At the same time, FERRO PTCR temperature measurement rings can be used in different firing atmospheres such as oxygen, nitrogen, air, vacuum and reduction. There are six types of ceramic temperature measurement rings available for users to choose from, with a temperature range of 850 ~ 1750℃. They can be distinguished according to the color of the ring and the production batch number and product code printed on the ring.
There are six existing PTCRs (649℃-1750℃) for users to choose according to the temperature range. (Operating range and model of temperature measurement ring (PTCR))

3. Operating Range, Model and Application Industry of Ferro PTCR Temperature Measurement Rings

4. Dimensions and Packaging of Ferro PTCR Temperature Measurement Rings

Dimensions of PTCR temperature measurement rings: outer diameter: 20mm, inner diameter: 10mm, thickness: 7.0mm. PTCR is a reliable high-precision product with a maximum error of less than 3℃, even up to 1.5℃. Product packaging: 15 pieces per small carton, 600 pieces per large carton.

5. Working Principle and Usage Method of Ferro PTCR Temperature Measurement Rings

1. FERRO PTCR temperature measurement rings have recognized accuracy and reliability. They can be placed almost anywhere in the kiln, in the furnace body, on the push plate or on the conveyor belt, and there is no need to measure the temperature before use.
2. The working principle of FERRO PTCR ceramic temperature measurement rings is based on their linear shrinkage within the working temperature range, so as to give the actual cumulative heat of the temperature measurement rings and the fired products. The test temperature is obtained by referring to the conversion table. After firing, the temperature measurement rings are taken away and marked.
3. When FERRO PTCR ceramic temperature measurement rings are heated in the kiln, they shrink and continue to shrink with the extension of holding time at the maximum temperature. Within its operating temperature range, the shrinkage rate is linear, which provides a practical measurement method for the heating amount received by FERRO ceramic temperature measurement rings and the fired products; the shrinkage (reduction in ring diameter) can be measured with a digital micrometer, and the handheld digital micrometer is used to record the diameter of each temperature measurement ring, accurate to 0.01mm.
4. Refer to the ring outer diameter and temperature comparison table and temperature correction curve attached to the package (provided with the product), and the measured diameter of the temperature measurement ring can be converted into equivalent temperature.

Please note that for accuracy and convenience in use, each temperature table of FERRO temperature measurement rings is specially formulated for that batch of temperature measurement rings, and the marked production batch number must be consistent with that on the temperature conversion table.

6. Determination of Kiln Temperature Distribution Diagram by Ferro PTCR Temperature Measurement Rings

Temperature measurement rings are widely used in continuous kilns, non-continuous tunnel kilns, shuttle kilns, roller kilns, bell kilns, etc. It is recommended to use multi-position and multi-level placement, which can give you the most direct understanding of the heat distribution in the kiln. FERRO PTCR temperature measurement rings can be used in different firing atmospheres such as oxygen, nitrogen, air, vacuum and reduction.

7. Advantages of Using FERRO Temperature Measurement Rings to Measure Kiln Temperature

1. FERRO temperature calibration rings / temperature measurement rings are flexible in use and can easily and conveniently measure any corner of the three-dimensional temperature distribution in the furnace.
2. The best placement position of FERRO temperature calibration rings / temperature measurement rings is close to the actual heating state of the product to accurately measure the actual heating situation of the fired products.
3. FERRO temperature calibration rings / temperature measurement rings have good consistency, which can ensure good reproducibility of the product firing system, thereby improving the qualified rate of finished products.
4. The use of FERRO temperature calibration rings / temperature measurement rings can reduce or even eliminate the need for measuring the geometry, density and porosity of fired products or destructive tests, thus reducing the quality control cost in the production process.
5. FERRO temperature measurement rings and ceramic temperature measurement rings are reliable high-precision products with recognized accuracy and reliability, and the accurate temperature difference is 1.5 - 3℃.

8. Cases of Improving Kiln Firing Product Quality with Temperature Measurement Rings

1. Application of temperature measurement rings in electronic ceramic product production
   Whether it is powder for electronic ceramics or electronic ceramic components such as capacitors, resistors and inductors, they have high requirements for electrical performance. Under the condition that the formula and production process are relatively fixed, the cumulative thermal effect of the fired products is a direct factor affecting the electrical performance of the products, and the thermal effect is mainly a comprehensive reflection of the firing temperature, holding time and firing atmosphere.
   Different firing temperatures, holding times and firing atmospheres will sinter products with different properties; the same batch of products with the same holding time but placed in different parts of the furnace may also produce products of different quality. In actual production, it is difficult to directly judge or select good products from the production process and put them into the next process, so the defective rate of the produced products is easy to be out of control. However, the temperature measurement points of various existing kilns are relatively fixed, and the distribution of the actual detection points of thermocouples is also limited, which is not conducive to accurately grasping the real state of products during firing.
   In addition, even if the temperature error caused by thermocouples of different materials and thermocouples of different ages when measuring temperature is ignored, thermocouples can only measure the radiant heat in the firing temperature, and cannot measure the comprehensive thermal effect of the conductive heat of kiln furniture, specific holding time and actual firing atmosphere. At this time, if several temperature measurement rings are placed before or during firing, not only can the actual temperature in the furnace be measured to adjust the furnace temperature in advance, but also the actual thermal effect of product firing can be reflected according to the diameter, color depth and shape change of the temperature measurement rings after being taken out of the furnace.
   Temperature measurement rings are small in size and easy to use. They can not only make horizontal comparison of products sintered in different kilns, but also retain the tested temperature measurement ring samples and data to make vertical comparison of products sintered in different periods, which provides a real historical basis for product quality tracking and better guarantees the strict management of product quality.
2. Using temperature measurement rings to solve the problem of large horizontal temperature difference in kilns
   The large horizontal temperature difference of industrial electric kilns easily leads to color difference defects in bricks produced in the same row of the kiln. This color difference is often in a gradual transition state, which is generally not easy to distinguish. The wider the kiln, the more obvious this defect is. In fact, there are many solutions to the temperature difference problem. The difficulty lies in how to accurately know the temperature difference in different positions of the kiln. Tests have shown that in polished brick production, the horizontal temperature difference in the firing zone of the kiln should be controlled to ≤5℃ as much as possible.
   Common temperature measurement equipment such as temperature measurement thermocouples are only set on one side of the kiln, so it is not easy to detect and control the horizontal temperature difference, so it is difficult to achieve uniform horizontal temperature. However, by using temperature measurement rings, because of their small size, they can accurately measure the kiln temperature at different positions and obtain the accurate value of the temperature difference in the kiln. On the one hand, it makes up for the deficiency of thermocouples; on the other hand, it measures the three-dimensional thermal distribution in the kiln.
   Then, by reasonably setting the air-oil (gas) ratio of each burner, correctly adjusting the valve opening, and timely adding refractory asbestos to prevent air leakage from the kiln wall and poor heat dissipation, it is much easier to solve the problem of temperature difference.
3. Application of temperature measurement rings in box-type electric furnaces
   Box-type electric furnaces are widely used in laboratories and small-piece product production. Because of their small investment and flexible use, they have become the preferred firing equipment. Because electronic ceramics and modern fine ceramics are very sensitive to firing temperature, a temperature deviation of 3-5℃ can cause obvious differences in product performance, so it is necessary to ensure the temperature uniformity in the box-type furnace. In actual use, due to the different settings of the heating elements of the box-type furnace, the temperature in the middle is often more uniform, while the temperature around is more unstable.
   In general, box-type furnaces are equipped with thermocouples for temperature measurement, but due to the limitation of the placement space of thermocouples, it is impossible to measure the temperature at various points in the furnace, so it is impossible to find out the temperature difference distribution in the furnace. It takes many tests to reasonably place the fired products, but the temperature difference will also change when the number or variety of products placed in the furnace changes. Therefore, a simple and convenient means is needed to measure the temperature in every corner of the furnace at any time.
   The temperature measurement ring is small, a small ring of 20mm * 7mm. Using several pieces and placing them anywhere in the furnace that needs to be measured, after firing and taking out of the furnace, measure their outer diameter and compare with the temperature comparison table to get the actual temperature at each point in the furnace. The measurement deviation is only within 3 degrees, which should be a good temperature measurement tool.
4. Application of temperature measurement rings in roller kilns
   Ceramic products are fired in roller kilns, which need to be carried out under a specific firing system. A reasonable firing system is the fundamental guarantee for obtaining good products. The firing system includes temperature system, pressure system and atmosphere system, among which the temperature system is the most critical. The temperature monitoring of the roller kiln mainly depends on the temperature data reflected by the thermocouples installed along the length of the kiln on the top or side of the kiln.
   Roller kilns are generally divided into preheating zone, firing zone and cooling zone. The temperature detection of the firing zone is mainly to determine the maximum temperature of the firing zone and the length of the high-temperature zone, that is, the time that the products stay at high temperature. The maximum temperature of the firing zone is the highest temperature point for porcelain formation, which directly affects the underfiring and overfiring of products. The length of the high-temperature zone affects the length of the holding time, thus affecting the product quality. Therefore, precise control of the firing temperature is the key to ensuring product quality. Sometimes the temperature indicated by the thermocouple reaches the firing temperature of the product, but due to different holding times, the product will also have great differences. The reason is that the thermocouple only measures the radiant heat at the position of its probe, and cannot record the comprehensive thermal effect such as the length of holding time for the product and the conductive heat generated by kiln furniture.
   Temperature measurement rings can record all the thermal effects accumulated by products during the firing process. They can provide a product firing situation different from that measured by thermocouples and other equipment. It is a better temperature measurement tool that is closer to the product and more truly reflects the heating of the product.
5. Application of temperature measurement rings in sintering electronic ceramics in vertical kilns
   Vertical kilns are widely used in the sintering of electronic ceramics due to their advantages of simple operation, uniform temperature and continuous sintering. For example: chip capacitors, PTC ceramic resistors, zinc oxide varistors and PZT piezoelectric ceramics. These products have high requirements for the accuracy of sintering temperature. If the temperature difference of similar products during sintering is too large, it will not only affect the consistency of the products, but also easily lead to the scrapping of the whole batch of products.
   The thermocouple probes of vertical kilns are generally arranged on the outside of the furnace chamber, and the temperature measured by them is not the actual temperature of product sintering. This requires that before sintering the products, not only the theoretical sintering temperature should be known, but also the difference between the actual temperature in the furnace chamber and the gauge temperature should be understood. Otherwise, it is difficult to burn high-quality products with the gauge temperature adjusted according to the theoretical temperature. At this time, using a temperature calibration ring to calibrate the temperature in the furnace chamber in advance can not only reduce the waste of materials, but also save valuable furnace testing time.
   The continuous sintering of vertical kilns makes each batch of products invisible during the sintering process. To ensure the quality of products after being taken out of the furnace, it is necessary to monitor with temperature measurement rings during the sintering process of each batch of products. Considering that thermocouples, like other instruments, will age or have low accuracy after being used for a period of time, and the heating elements themselves are also easy to age, regularly (for example, once a day) putting temperature measurement rings into the sintering of electronic ceramic products can monitor the furnace temperature change state of the sintered products. In the long run, using temperature calibration rings as a monitoring means in sintering products in vertical kilns can ensure the quality and consistency of products.
6. Application of temperature measurement rings in magnetic materials
   In the production and research and development of nickel-zinc, manganese-zinc-cobalt, neodymium-iron-boron and other magnetic materials, it is necessary to formulate the firing temperature for the production process temperature (calcined material temperature) of new materials; the secondary magnetic material products also need accurate kiln temperature for sintering to stabilize the electrical performance indexes of magnetic products. Kilns generally transmit kiln temperature through thermocouples, but due to factors such as different manufacturers, different kilns and different specifications, it is difficult to unify the temperature measurement standards in the same enterprise, which easily leads to inconsistency between the firing temperature tested by the R & D department and the actual temperature control of the production department, bringing inconvenience to production.
   Temperature measurement rings can accurately provide the actual temperature effect inside the furnace chamber (that is, the cumulative thermal effect of the product), track the quality of the cumulative heat required for magnetic materials, and objectively record the daily temperature changes in the furnace chamber, providing accurate data information as the file data for temperature quality tracking, which is conducive to the implementation of the ISO quality tracking management system, the unification of internal R & D and production temperature control standards, and reducing the complexity of sintering temperature changes caused by different batches of raw materials.