Annealing with Induction

Improve your annealing process without flame! Induction heating focuses energy in your part only. You don't need a torch or a costly batch or furnace process. Anneal your materials in a repeatable, precise flameless process.

Annealing is a heat treatment in which a material such as copper is exposed to an elevated temperature for an extended time and then slowly cooled. Annealing heat treatments are largely characterized by induced microstructural changes which are ultimately responsible for altering the material's mechanical properties. The ultimate goal of this process is to reduce the hardness of the metal and improve its ductility.

Annealing refers to the process of bringing the material to its softest possible point. A tempering process softens the metal but not to the full extent possible.

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Any annealing process consists of three stages. First, the metal part is placed inside an induction coil and power is supplied until the part reaches the correct temperature. The temperature can be checked with an optical pyrometer, temperature sensing paint or some other temperature-sensing device. The second stage is holding or soaking at the correct temperature, which can be accomplished with a closed loop temperature control system. The annealed part must then be allowed enough time to cool down to room temperature.

Metal to be annealed:
Temperature Sensing Device: The temperature of the metal must be checked with an optical pyrometer, temperature sensing paint or other sensing mechanism.
Closed Loop Temperature Control System: The control system monitors and constantly adjusts the output of the power supply so as to maintain the correct surface temperature on the part. This allows the core of the part to reach a uniform temperature. A typical system would include the power supply, heat station, coil and an optical pyrometer.
Heat source: Fast, precise heating works best.

Flux: The functions of flux are to dissolve the oxides formed during the heating process, shield the alloy and joint from oxidation, provide clean surfaces to promote even spreading of the alloy, and to promote alloy flow by capillary actiona phenomenon associated with surface tension and resulting in the elevation or depression of liquids in capillaries . There are many different types of fluxes available for use at different temperature ranges. Black flux is used for high temperatures (up to 1800°F) and is good for steel brazing. White flux is most often used for lower temperature (1100°F to 1500°F) applications. Ideally, the flux should have a lower melting point than the base metal, and should be entirely liquid before the braze alloy melts.

Heat source: Fast, precise heating works best.

Modern induction heating provides many advantages over other heating methods and is commonly used for annealing applications such as copper pipe bending. Heating through induction provides reliable, repeatable, non-contact and energy-efficient heat in a minimal amount of time without the use of flame or torch. Solid state systems are capable of heating very small areas within precise production tolerances, without disturbing individual metallurgical characteristics.

Induction can be used for either surface or through heating; case annealing is possible depending on time, temperature and the material's characteristics.

The degree of temper depends on the material, the maximum temperature reached and the length of the cool down time. Process or Stress Relief Annealing is used to negate the effects of cold work; that is, to soften and increase the ductility of a previously strain-hardened metal. Internal stresses may develop as a result of plastic deformation processes such as machining or grinding, non-uniform cooling in a welding or casting process, or a phase transformation. Distortion and warping may occur if the internal stresses are not removed. Annealing will eliminate these stresses when the part is heated to the recommended temperature, held there long enough, and slowly cooled to room temperature.

Closed loop control, through the use of an optical pyrometer or other temperature sensing device, can provide constant heat with a tolerance as low as 3°C at 700°C. Induction heating also ideal for in-line production processes because of its ability to produce repeatable, rapid and accurate heating cycles.

Induction systems typically used for induction annealing range from 1 to 20kW, depending on the parts and application requirements.

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annealing steel annealing_33 Annealing copper tubes to create formed tubes and pipes Annealing copper tubes to create formed tubes and pipes Induction offers the same result every time, which makes it ideal for a high volume process such as this one. The previous oxidation issue forced them to polish the handles which added a step in their manufacturing process. apps_able.php
annealing steel annealing_32 Annealing a stainless steel handle Annealing a stainless steel handle Induction offers the same result every time, copper tubes of various geometries heated to temperature in a matter of seconds, which makes it ideal for a high volume process such as this one. apps_able.php
annealing stainless steel annealing_31 Annealing ammunition casings Annealing ammunition casings Induction offers the same result every time, while a torch often delivers variation and there is no open flame with induction. apps_able.php
annealing stainless steel annealing_30 Annealing stainless steel tubes Annealing stainless steel tubes The client’s parts were heated to the desired temperature in less than three seconds. Their gas oven required twice as much heating time as the induction process. Induction is more energy-efficient and requires less space compared to a gas oven. apps_able.php
annealing copper annealing_27 Annealing stainless steel tubing Annealing stainless steel tubing Looking to replace an inefficient oven process, part is heated in just 30 seconds, improving efficiency for this application apps_able.php
annealing copper annealing_25 Annealing a copper wire connector (crimp) Annealing a copper wire connector (crimp) The client wanted to be able to heat parts of various sizes, which was achieved with a concentrator coil. This is a new process for the client, and Ambrell’s lab expertise proved very valuable when creating the process. apps_able.php
annealing copper annealing_23 Annealing steel wire for a medical application Annealing steel wire for a medical application The wire achieved the targeted temperature within three seconds. By bringing their process in-house, the client will have better control over the end product. Ambrell was able to perform a free laboratory test and design a process that could enable the client to bring the process in-house in a cost efficient manner, and even connect them with an automation partner to maximize productivity apps_able.php
annealing stainless steel annealing_22 Annealing stainless steel caps for a dental application Recozimento de tampinhas de aço inox para aplicação dentária Requirement to anneal large quantities of work-hardened crowns suggests induction for precise, controllable heating. Since oxidation is unacceptable in the finished product, Induction is the appropriate choice for heating in an inert atmosphere.  apps_able.php
annealing brass/bronze annealing_21 Annealing brass and bronze tubing prior to bending to form handrails Recozimento de tubulação de latão e bronze antes de dobrados para formar um corrimão A twelve-turn helical coil is used to heat an 8” (20.3cm) area 3” (7.6cm) above the end of the tube. Each of the four tubes require a different heat cycle and time to reach the required temperature. apps_able.php
annealing zinc annealing_20 Annealing a zinc wire prior to forming pellets for air rifles Recozimento de arame de zinco antes de formar grãos para rifles de ar A fourteen-turn coil is used to heat 3.9” (100mm) of zinc wire. The wire is placed in the coil for 5 seconds to reach the desired condition just prior to the forming process. apps_able.php
annealing steel annealing_19 Annealing the end of a hydraulic motor shaft prior to machining Recozimento da extremidade de um eixo de motor hidráulico antes da usinagem A three-turn helical coil is used for annealing the motor shaft. The end of the motor shaft is placed in the coil and power is applied for 20 seconds to reach 1350 ºF (732 ºC) and turn the steel red hot. apps_able.php
annealing aluminum annealing_18 Annealing aluminum fuel tank fill neck for bending Recozimento para dobra de pescoço de alumínio para abastecimento de tanque de combustível An eight turn helical is used to heat the tube for annealing. To anneal the full length of the tube, the tube is placed in the coil and heated. apps_able.php
annealing stellite annealing_17 Annealing of stellite tips on saw blades Annealing of stellite tips on saw blades A split four turn helical coil is used so the blade can move evenly though the coil. Each tip of the blade is heated for 5 seconds as it passes through the coil to anneal the affected area. apps_able.php
annealing copper annealing_16 Continuous annealing of copper wire Recozimento contínuo de arame de cobre A twelve turn helical coil is used. A ceramic tube is placed inside the coil to isolate the copper wire from the copper coil and to allow the copper wire to flow smoothly through the coil. Power runs continuously to anneal at a rate of 16.4 yds (15m) per minute.. apps_able.php
annealing steel annealing_15 Annealing lip on cryogenic dewar Recozimento de virola em vaso de dewar criogênico A two turn helical coil is used to heat the lip on the cryogenic dewar. The dewar is placed in the coil and power is applied for 2 minutes to anneal the required 1” heat zone. apps_able.php
annealing steel annealing_14 Anneal an oval cut-out on a stainless steel tube prior to extrusion Recozer recorte oval em tubo de aço inoxidável antes da extrusão A single turn helical coil is used on the 4” (101.6mm) diameter tubes and a two turn helical coil is used on the smaller diameters. apps_able.php
annealing   annealing_13 Annealing the end of steel wire on a woven wire mesh Recozimento de extremidade de arame de aço em uma malha de arame trançado Induction heating provides faster production process, high efficiency, low energy costs compared to gas furnace, fast, controllable process and hands-free heating that involves no operator skill for manufacturing. apps_able.php
annealing   annealing_12 Annealing both ends of copper tubing for refrigeration Recozimento das extremidades de uma tubulação de cobre para refrigeração Induction heating provides controlled application of heat to very specific area, faster process time, increased production and high efficiency, low energy cost. apps_able.php
annealing   annealing_11 Annealing brass electrical contact for crimping Recozimento de contato elétrico de latão para crimpagem Induction heating provides hands-free heating that involves no operator skill, pinpoint accuracy and consistent results apps_able.php
annealing   annealing_10 Annealing a steel shaft for stress relief Recozimento de eixo de aço para aliviar tensões Flameless induction heating allows formerly batch process to be done in-line saving time and energy. No rotation of part needed. apps_able.php
annealing stainless steel annealing_9 Annealing bolt shafts Recozimento de um eixo de parafuso A three turn helical coil is used to heat the shaft of the bolts for 10 to 12 seconds on the large bolts and 18 to 20 seconds on the smaller bolts using the same coil. apps_able.php
annealing   annealing_8 Annealing Lock Nuts Recozimento de contraporcas A three turn helical coil is used to heat the locknut to 2150ºF for 5 seconds. Induction heating provides repeatable, rapid and accurate heating cycles making it ideal for in-line production processes apps_able.php
annealing   annealing_6 Annealing stainless steel bread cutting saw blades Recozimento de lâminas de corte de pão em aço inoxidável Induction heating provides improved quality of blades at hole punching location, decreased scrap product and is easily incorporated into existing production lines apps_able.php
annealing   annealing_7 Anneal the end of metal stamp sets Recozimento de extremidade de conjuntos de estampagem metálicos One five-turn and two four-turn helical coils are used to heat the end of stamps to the required temperature. Two part sizes can be run in each of coils, using the same machine settings except for cycle time. apps_able.php
annealing   annealing_5 Annealing Tungsten Rods Recozimento de hastes de tungstênio A multi turn induction heating coil is designed for heating the various rod diameters. An optical pyrometer is used to measure the temperature of the part inside the induction coil. apps_able.php
annealing   annealing_4 Band annealing on Titanium fasteners Recozimento de faixa de acessórios de fixação de titânio Induction heating can be incorporated easily with pick and place robotics, delivers a flameless process in which heating is limited to the specific area. apps_able.php
annealing   annealing_3 Annealing Brazing Wire Recozimento de arame de brasagem Induction heating provides higher productivity of 27’ (8.2m) per minute, a reduction in surface oxidation & scaling with consistent, repeatable results apps_able.php
annealing   annealing_2 Selectively Annealing Thread Ring Gauge Blocks Recozimento de blocos de anel de calibre de rosca To selectively and uniformly anneal two sections of a thread ring gage block from the hole to the outside surface from a hardness of Rc 59-61 to Rc 45. apps_able.php
annealing   annealing_1 Achieving Uniform Hardness on Saw Blades Obter dureza uniforme em lâminas de serra Resulting mean hardness of 50.3 Rc was measured for fifteen saw teeth on a Wilson Superficial Hardness Tester, fulfilling the ultimate goal established by the customer. apps_able.php