High Temperature Annealing

At Thomson Lamination Company (TLC), we stamp a variety of a laminations made from specialty electrical steel alloys used in high-performance rotating components such as fractional horsepower motors, servos, synchro’s, resolvers, gyros, and other motor parts. Due to this specialized component production, TLC places major emphasis on providing the most sophisticated and modern annealing facility in our industry.


Our ability to meet critical annealing temperature tolerances and specifications ensures the ideal magnetic properties of the laminations, as well as the maximum performance of the end-products in which they are installed. The versatility and accuracy provided in our annealing facility have established subcontract annealing of customer laminations and parts as one of our standard services. For this reason, our team includes a full-time metallurgist to coordinate the annealing requirements of our customers. 


Annealing Process – Fully Processed Non-Oriented Electrical Steel

The magnetic properties of fully processed electrical steels are completely developed by the steel producer. These alloys are typically ready to use without any additional processing to obtain the required magnetic properties of ASTM A677. A Stress Relief Anneal (SRA) can be used to eliminate any stresses that were introduced from the fabrication and or stamping process. The stress relief annealing (SRA) process can be performed using a continuous furnace or a batch type furnace. Each type of furnace has its advantages.

Continuous Process

Continuous SRA process is used for high volume production. Due to the continuous nature of the process, the cycle time should be as short as possible but care must be taken not to impart thermal stresses in the material during the heat up or cooling portion of the SRA. The metal volume of any given mass should be small enough for the load to quickly reach annealing temperature. Advantages of continuous SRA are high volume of laminations, lower lead time and lower price per part.   

Batch Process

Batch SRA process uses a retort type furnace and is used for low volume production. The batch process is more flexible in utilizing different temperatures and soak times if needed. The flexibility the batch process has its disadvantages, higher lead times and higher price per part.  

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Batch Annealing – 49% Nickel – Carpenter Hi Perm 49

Carpenter High Permeability 49 alloy is a 48% nickel-iron alloy that has high saturation flux density, high magnetic permeability and low core loss. Carpenter High Permeability 49 alloy has been used in the manufacturer of rotor and stator laminations in motors, instrument transformers, magnetic shields and cores for certain electronic and communications devices in which extremely high permeability at low magnetizing forces greatly increases the efficiency and effectiveness of the equipment. Carpenter High Permeability 49 requires oxygen free, dry hydrogen anneal. 

Batch Annealing – 80% Ni – Carpenter HyMu 80

Carpenter HyMu 80 alloy is a non oriented, 80% nickel-iron-molybdenum alloy which offers extremely high initial permeability as well as maximum permeability with minimum hysteresis loss. Carpenter HyMu 80 alloy has been used primarily in transformer cores, tape wound toroid’s and laminations where compactness and weight factors are important. It has also been used for shielding to protect electrical components from stray magnetic fields. Carpenter HyMu 80 requires oxygen free, dry hydrogen anneal.

Batch Annealing – Cobalt Alloys – Carpenter Hiperco 50

Carpenter Hiperco 50 is an iron-cobalt-vanadium soft magnetic alloy which exhibits high magnetic saturation, high D.C. maximum permeability, low D.C. coercive force and low A.C. core loss. Hiperco 50 has been used in the manufacturer of rotor and stator laminations in motors and generators for aircraft power generation applications. Hiperco 50 requires oxygen free, dry hydrogen anneal at temperatures ranging from 1400 F to 1600 F depending on the required mechanical/magnetic properties.

Oxide Coating

TLC can also provide an oxide coating on all of its lamination alloys to comply with customer needs and specifications.  

High Temperature Annealing with Thomson Lamination Co.

Thomson Lamination Company has the necessary expertise and state-of-the-art equipment to provide a standard stress relief anneal (SRA), and high-temperature annealing up to 2150 F for motor laminations from our Nadcap-certified facility. TLC has held Nadcap accreditation since 2010. Having demonstrated its ongoing commitment to quality by satisfying customer requirements and specifications, the Nadcap Task Group has determined that Thomson Lamination Company has earned the longest accreditation period possible.  


TLC offers several types of annealing services for motor laminations.

Fully Processed Non Oriented Electrical Steel

  • Continuous Stress Relief Anneal (SRA) 1425 F, a TLC standard
  • Batch Retort SRA (1250 F – 1450 F)

49% Ni and 80% Ni – Carpenter High Permeability 49, HyMu 80

  • Batch Retort 1700 F – 2150 F
  • Bell Retort 1700 F – 2150 F

Cobalt Alloys – Hiperco 50

  • Batch Retort 1250 F – 1600 F
  • Bell Retort 1250 F – 1600 F

Oxide Coating: 600 F – 900 F

Get in Touch

Contact us or request a quote for more information about motor laminations and custom annealing solutions available from Thomson Lamination Company.