tain temperature with a ±25 thou temperature tolerance, other grades might require a ±5 or 10°,” says Schmidt, who explains there are a variety of testing that can be requested depending on the nature of the application and industry serving.
WHAT ARE SOME CHALLENGES?
PHOTO: THERMEX METAL TREATING
then quenching it, which means cooling it quite rapidly to change the micro-structure. This process creates movement. Customers will call it distortion but it is movement in the steel which is byproduct of successful heat treatment.”
QUALITY CONTROLS For the most part quality assurances are dictated by the customers and specifications. It can be as easy as just certifying the process or as complicated as reviewing the micro-structure of a coupon. Many heat treating companies have dedicated quality departments to ensure their processes are done correctly, especially when it comes to industries requiring stringent standards, like aerospace. One of the challenges heat treating facilities face is working with proprietary specifications. For Hanson, “working with the oil industry, most of the big players, like Haliburton or Schlumberger, they all have their own proprietary standards that we have to work towards, so often we will have a discussion with our customers about that as well.” They have developed an in-house metallurgical lab to test their products extensively to ensure they are meeting the requirements. Understanding the different requirements both from customers and industry can make the heat treating process go more smoothly. “Most of the grades have their own unique recipes involved. It also requires more stringent parameters in the furnace itself. Some of the exotic materials and the industries they serve require tight temperature tolerances, so certain things can be run at a cer96 | AUGUST 2015
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One of the most important challenges is just making sure that heat treating companies are able to meet the appropriate specifications. For Hanson, who’s primary customer is a machine shop selling to end users, this can be a challenge, because he has to ensure that he not only meets the shop’s specification but also the end user’s needs. Different types of materials are required for different applications. There are specific heat-treatment processes associated with each to achieve optimum results. “Hence, when designing a part for a particular application, always analyze different steels to find the one that provides the balance of hardness, strength, amongst other characteristics to withstand the stresses the part will undergo in use as a finished part,” explains Bawa. As a heat treating customer, it is important to ensure that part you provide is within the appropriate conditions for the process, which should include movement and distortion. “Some customers tend to take this for granted,” says Schmidt. When you elevate the hardness of materials, it can make it harder to post-process machine. So customers will often machine to close to tolerance, being motivated to do as little machining after as possible. “There is a fine line and some risk involved,” he continues. “So they are rolling the dice by machining it too closely prior to heat treat. They may not be able to clean it up afterwards.” When it comes to heat treating, there are many variable involved. Finding the correct heat treating facility for your needs will help ensure that the finished product is up to spec. Speak to the facility; their expert advice can help ensure that you’ve chosen the right process for the material and outcome expectations. Heat treating is one of the key and fundamental steps used in producing machined or hardened metal parts. “It has applications across so many different industries and requirements. Any city, area, or region that wants to have a good strong metal parts manufacturing sector has to have good heat treating facilities available,” says Hanson. www.canadianmetalworking.com
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