| Ferro（PTCR）Process Temperature Control Rings |
| Effective temperature measurement is required in the production of ceramic products, but most measurements are limited in time and space For example, thermocouples cannot measure the temperature of the product itself, but rather the ambient temperature of the product In addition, it can only measure radiant heat and does not involve conduction heat from kiln furniture PTCR high-precision ceramic firing temperature indicator is used to record the actual firing process of the finished product (including radiation heat and conduction heat), suitable for non continuous kilns and continuous tunnel kilns, as well as for atmospheres such as oxygen, nitrogen, air, vacuum, and reduction. |
| 1. Function | | The performance of electronic ceramic products is not only determined by the formula, but also by the firing process, which is the most critical factor. The comprehensive thermal effects of ceramic firing generally include firing temperature, insulation time, and kiln atmosphere. Various types of kilns are required in industrial product production and practical research, such as box furnaces, tube furnaces, vertical kilns, tunnel kilns, bell kilns, roller kilns, etc. Effective temperature control is required for electronic ceramics, magnetic materials, and powder metallurgy heat treatment. However, most temperature measurement methods (such as thermocouples, cones, photometers, etc.) are limited in time and space. In practical use, they can only measure the ambient temperature of the product, and it is difficult to measure the heat conduction and radiation from different directions, as well as the cumulative heat effect of the product itself with different insulation times. In fact, the comprehensive thermal effect in the production of ceramic products directly affects the firing quality of the products. Adopting not only solves the limitations of time and space, but also simultaneously measures the radiation heat and conduction heat of the kiln, as well as the comprehensive thermal effect of the entire firing process of the product. | |
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 | The entire production process of PTCR by Ferro Corporation in the United States has obtained ISO9002 quality certification, ensuring product accuracy, reliability, and convenience from all aspects (including the control of the original selection production process and the development of product inspection conversion tables). | |
| 2、 Ferro PCTR 850~1750 ℃ Ceramic Product Introduction | Many high-temperature refractory products require 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 rather the ambient temperature during the firing process. Thermocouples record the temperature obtained at the top, which is only a point in space and time. A thermocouple cannot determine the heating process; A thermocouple cannot provide information on whether the furnace heats uniformly in different directions. It can only measure radiant heat and does not involve the conduction heat from the furnace equipment.
FERRO PTCR ceramic is a high-precision ceramic temperature indicator that faithfully records the thermal process experienced by the product during the firing process.
FERRO PTCR ceramics not only measure radiant heat and radiation heat, but also consider the effect of temperature over time.
FERRO PTCR ceramics can easily represent the heating process with a simple number - ring temperature (RT), which is convenient for practical applications.
Widely used in continuous and discontinuous tunnel kilns, shuttle kilns, roller kilns, bell jar kilns, etc., it is recommended to use multi position and multi-level placement, which can give you a direct understanding of the thermal distribution inside the kiln.
Meanwhile, FERRO PTCR can be used in different firing atmospheres such as oxygen, nitrogen, air, vacuum, and reduction.
There are six types of ceramics available for users to choose from, with a temperature range of 850-1750 ℃. They can be distinguished based on the color of the ring and the production batch number and product code printed on the ring. | |
| There are currently six types of PTCR (649 ℃ -1750 ℃) that users can choose from based on the temperature range (PTCR) Scope and Model of Work |
| 3、 The scope, models, and application industries of Ferro PTCR |
| temperature range | model | color | Application Industry | | 649～1000°C | RTC —AQS | green | Low temperature refractory materials, daily-use ceramics, art ceramics, ceramic tiles, and kiln furniture | | 850～1100°C | PTCR—ETH | light green | Low temperature refractory materials, daily-use ceramics, art ceramics, ceramic tiles, and kiln furniture | | PTCR - ETL | | 970～1250°C | PTCR—LTH | pink | Ceramic pre synthesis, ceramics, building bricks and tiles, low-temperature refractory materials, and kiln furniture | | PTCR-LTL | | 1130～1400°C | PTCR—STH | green | Single layer and multi-layer capacitors, ferrites and insulating ceramics, sanitary ceramics, powder metallurgy, daily-use ceramics, bricks and tiles, grinding wheels, medium temperature refractory materials, and kiln furniture | | PTCR - STL | | 1340～1520°C | PTCR—MTH | yellow | Magnetic materials, insulating ceramics, porcelain, dielectric ceramics, piezoelectric ceramics, semiconductor ceramics, other optical functional ceramics, biological and chemical functional ceramics, medium to high temperature refractory materials, kiln furniture | | PTCR - MTL | | 1450～1750°C | PTCR—HTH | white | Special structural ceramics, special functional ceramics, substrates, high-temperature refractory materials, and kiln furniture | | PTCR - HTL | |
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| 4、 Ferro PTCR size and packaging |
PTCR size: 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/small paper box, 600 pieces/large box. | 
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| 五、 Ferro PTCR 工作原理及使用方法： |
| 1. FERRO PTCR has excellent performance and reliability, and can be placed almost anywhere in the furnace, inside the furnace body, on the push plate or conveyor belt, without the need to measure temperature before use; 2. The working principle of FERRO PTCR ceramics is based on its linear shrinkage within the working temperature range, which provides the actual cumulative heat of the fired product. The test temperature is obtained by comparing it with a conversion table. After firing, it is taken away and marked; 3. When FERRO PTCR ceramics are heated in a kiln, they shrink and continue to shrink with increasing insulation time at high temperatures. Within its operating temperature range, the shrinkage rate is linear, providing a practical measurement method for the amount of heating experienced by FERRO ceramics and fired products; The shrinkage (reduction in ring diameter) can be measured using a digital micrometer, and the diameter of each piece can be recorded using a handheld digital micrometer up to 0.01mm; 4. Refer to the outer diameter and temperature comparison table and temperature correction curve chart attached on the packaging (provided with the product), the measured diameter can be converted into equivalent temperature. Please note that each temperature gauge of FERRO is specially designed for this batch for ease of use, and the production batch number marked must be consistent with the temperature conversion table. |
| 6、 Ferro PTCR measurement of kiln temperature distribution map |
Widely used in continuous and discontinuous tunnel kilns, shuttle kilns, roller kilns, bell jar kilns, etc., it is recommended to use multi position and multi-level placement, which can help you control the heat inside the kiln
The branch has a direct understanding.
FERRO PTCR can be applied in different firing atmospheres such as oxygen, nitrogen, air, vacuum, and reduction. | 
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| 7、 Advantages of using FERRO measurement in kilns: |
1. The FERRO temperature calibration ring is flexible and easy to use, allowing for easy and convenient measurement of temperature distribution in any corner of the furnace's three-dimensional space.
2. The FERRO temperature calibration ring/placement position is close to the actual heating state of the product, and the actual heating condition of the burned product is measured.
3. The FERRO temperature calibration ring has good consistency, which can ensure good reproducibility of the product firing system, thereby improving the qualification rate of the finished product.
4. The use of FERRO temperature correction rings can reduce or even eliminate the need for geometric shape, density, and porosity measurements or destructive testing of burnt products.
Thus reducing the cost of quality control in the production process.
5. FERRO ceramics are reliable high-precision products with excellent performance and reliability, with a temperature difference of 1.5-3 ℃. | 
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| 8、 Case study on improving the quality of kiln fired products |
| 1. Application in the production of electronic ceramic products
| | Whether it is powders for electronic ceramics or electronic ceramic components such as capacitors, resistors, inductors, etc., the requirements for electrical performance are high. In the case where the formula and production process are relatively fixed, the cumulative thermal effect of the fired product is a direct factor affecting the electrical performance of the product, and the thermal effect is mainly a comprehensive reflection of the firing temperature, insulation 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 insulation time, but placed in different parts of the furnace, may also produce products of different qualities. In actual production, it is difficult to directly judge or select good products from the production process and put them into the next production process, which can easily lead to a loss of control in the defect rate of the produced products. However, the temperature measurement points of various types of kilns are relatively fixed, and the distribution of actual detection points of thermocouples is also limited, which is not conducive to grasping the true state of products during firing. In addition, even if the temperature errors caused by thermocouples of different materials and thermocouples of different ages are ignored when measuring temperature, thermocouples can only measure the radiation heat in the firing temperature, and cannot measure the conduction heat of the kiln furniture, the specific insulation time, and the comprehensive thermal effect of the actual firing atmosphere. At this time, if several pieces are placed before or during firing, not only the actual temperature in the furnace can be measured and the furnace temperature can be adjusted in advance, but also the actual thermal effect of product firing can be reflected according to the diameter, color depth and shape change after firing. Small in size and easy to use, not only can products sintered in different kilns be compared horizontally, but also the tested samples and data can be retained for vertical comparison of products sintered at different stages. This provides a real historical basis for tracking product quality and ensures strict management of product quality. | | 2. Using to solve the problem of large lateral temperature difference in kilns
| | The lateral temperature difference of the kiln is too large, which can easily lead to color difference defects in the bricks produced in the same row of the kiln. This color difference often presents a gradual transition and is generally difficult to distinguish. The wider the kiln, the more obvious this defect becomes. There are actually many solutions to the problem of temperature difference. The challenge lies in accurately knowing the temperature difference at different positions inside the kiln. Experimental results have shown that in the production of polished tiles, the lateral temperature difference of the kiln firing zone should be controlled as much as possible to be ≤ 5 ℃. Common temperature measuring devices such as thermocouples are only installed on one side of the kiln, making it difficult to detect and control the lateral temperature difference, making it difficult to achieve uniform lateral temperature. By using it, due to its small size, it can accurately measure the kiln temperature at different positions and obtain the value of the temperature difference inside the kiln. On the one hand, it compensates for the shortcomings of thermocouples, and on the other hand, it measures the three-dimensional thermal distribution inside the kiln. By setting the air oil (gas) ratio of each burner reasonably, adjusting the valve opening correctly, and timely adding refractory asbestos, it is much easier to solve the problem of temperature difference by preventing air leakage and poor heat dissipation in the kiln wall. | | 3. Application in Box type Electric Furnace
| | Box type electric furnaces are widely used in laboratories and the production of small products, and have become firing equipment due to their low investment and flexible use. Due to the high sensitivity of electronic ceramics and modern fine ceramics to firing temperature, a temperature deviation of 3-5 ℃ can cause significant differences in product performance. Therefore, it is necessary to ensure the uniformity of temperature inside the box furnace. In practical use, due to different settings of heating elements in box furnaces, the temperature in the middle is often more uniform, while the temperature around is less stable. In general, box type furnaces are equipped with thermocouples for temperature measurement. However, due to the limited space for placing thermocouples, it is impossible to measure the temperature at various points inside the furnace. Therefore, the distribution of temperature differences inside the furnace cannot be determined. For the placement of burnt products, multiple experiments need to be conducted to make it reasonable, 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. Small volume, 20mm * 7mm small circular ring. Using a few pieces, place them anywhere in the furnace that needs to be measured. After firing, measure their outer diameter and compare them with the temperature comparison table to obtain the actual temperature of each point in the furnace. The measurement deviation is only within 3 degrees, which should be a good temperature measuring tool.
| | 4. Application in roller kilns
| | Ceramic products need to be fired in a roller kiln under a specific firing system, and 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 roller kilns mainly relies on the temperature data reflected by thermocouples installed on the top or side of the kiln along its length. 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 highest temperature of the firing zone and the length of the high temperature range, that is, the time the product stays at high temperature. The highest temperature of the firing zone is the highest temperature point for porcelain formation, which directly affects the raw and over firing of the product. The length of the high temperature range affects the length of the insulation time, and thus also affects the quality of the product. Therefore, controlling the firing temperature is the key to ensuring product quality. Sometimes the temperature indicated by the thermocouple reaches the temperature point at which the product is fired, but due to different insulation times, there can be significant differences in the product. The reason is that the thermocouple only measures the radiant heat at the location of its probe, and cannot record the comprehensive thermal effects of the product, such as the length of insulation time and the conduction heat generated by the kiln furniture. It can record all the accumulated thermal effects of the product during the firing process. Can provide a product firing situation that is different from the measurement reflection of devices such as thermocouples. It is a better temperature measurement tool that is closer to the product and reflects the product's heating more realistically.
| | 5. Application in vertical kiln sintering of electronic ceramics
| | Vertical kilns are widely used for sintering electronic ceramics due to their advantages of simple operation, uniform temperature, and continuous sintering. For example, ceramic capacitors, PTC ceramic resistors, zinc oxide varistors, and PZT piezoelectric ceramics. The accuracy requirements for the sintering temperature of these products are high. If there is a large temperature difference during the sintering process of similar products, it will not only affect the consistency of the products, but also easily lead to the scrapping of the entire batch of products. The thermocouple probe of a vertical kiln is generally arranged on the outside of the furnace, and the temperature it measures is not the actual temperature of the product sintering. This requires not only to know the theoretical sintering temperature of the product before sintering, but also to understand the difference between the actual temperature inside the furnace and the header temperature. Otherwise, the header temperature adjusted according to the theoretical temperature will be difficult to produce high-quality products. At this point, using a temperature calibration ring to check the temperature inside the furnace in advance can not only reduce material waste, but also save valuable trial furnace time. The continuous sintering of the vertical kiln also makes each furnace product in an invisible state during the sintering process. To ensure the quality of the products after they are fired, it is necessary to monitor them during the sintering process of each batch of products. Considering that thermocouples, like other instruments and meters, will age or have lower accuracy after a period of use, and heating elements themselves are also prone to aging, they can be placed regularly (such as once a day) during the sintering of electronic ceramic products to monitor the temperature changes of the sintered products. In the long run, using a temperature calibration ring as a monitoring tool for sintering products in a vertical kiln can ensure the quality and consistency of the products.
| | 6. Application in magnetic materials
| | In the production and research and development process of magnetic materials such as nickel zinc, manganese zinc cobalt, neodymium iron boron, etc., it is necessary to determine the firing temperature (pre firing material temperature) for the production process of new materials; Accurate kiln temperature is also required for sintering secondary magnetic material products in order to stabilize the electrical performance indicators of the magnetic products. Kilns generally transmit kiln temperature through thermocouples, but thermocouples are difficult to unify temperature measurement standards within the same enterprise due to different manufacturers, kilns, specifications, and other factors. This can lead to discrepancies between the firing temperature tested by the R&D department and the actual temperature control by the production department, causing inconvenience to production. Being able to accurately provide the actual temperature effect inside the furnace (i.e. the cumulative heat effect of the product), and track the quality of the accumulated heat required for magnetic products, while objectively recording the daily temperature changes inside the furnace, providing accurate data information as archive data for temperature quality tracking, is conducive to implementing the ISO quality tracking management system, achieving the unity of internal R&D and production temperature control standards, and reducing the complexity of sintering temperature changes caused by different batches of raw materials. | |
