Hot Flattening & Straightening
Often, heat treatments can warp or bend alloys used to make important parts that must be flat to fit together seamlessly.
Expert Flattening for Better Parts.
During metal fabrication, flat and straightened materials are critical for a correct fit and weld. Heat treating and quenching can leave parts slightly warped and unable to fit correctly. Paulo utilizes a variety of processes to straighten and flatten alloys using computer-controlled machinery and overseen by our metallurgical experts to deliver clean, consistent results for every part, every time.
Paulo’s Straightening and Flattening Services
Mechanical straightening
Hand tools and presses are used to straighten parts after heat treatment. Gauges or other measurement devices are used to verify parts meet straightness requirements. Â
Hot flattening
Parts are clamped between large dies and heated to achieve flatness.
The Paulo Edge.
Distortion is often unavoidable in heat treatments. Our state-of-the-art equipment and facilities allow us to handle high volume straightening and flattening jobs to ensure your parts work for their intended purpose. Our manual and hydraulic presses can flatten up to 100 tons, with flattening and clamping fixtures for parts up to 36 inches in diameter. We also utilize a 19-roll straightener for parts up to .5 inch thick and large, computer-controlled furnaces for multiple clamping fixtures.
Flattening and Straightening FAQs
Can you fix warpage or distortion that happens during heat treatment?
Yes. Some level of distortion is inevitable during heat treatment due to the metallurgical transformations and thermal expansion/contraction that occur during the process. Paulo offers several solutions to bring parts back into specification:
Mechanical straightening uses a manual and hydraulic presses (up to 100 tons of capacity) combined with precision gauges and measurement devices to verify parts meet your straightness requirements.
Hot flattening is our primary method for correcting distortion in flat components. Parts that come out of heat treatment with as much as 0.025″ of variance can often be brought back within 0.010 – 0.015″ using our clamp and temper process. We can achieve flatness within 0.010″ (ten thousandths of an inch) for many applications.
Is there any risk to flattening or straightening my parts?
With straightening, there is an inherent risk because you’re applying bending force to heat-treated (hardened) material. Our operators use careful techniques and years of experience to minimize this risk, but it’s important to understand that the possibility of cracking exists, particularly with certain geometries or highly hardened materials.
Hot flattening carries significantly lower risk because the process works by relieving stresses rather than forcefully bending the material. During hot flattening, parts are clamped flat and then heated to a tempering temperature that allows the material to relax into its flattened position. This makes it a safer, more controlled process—especially for production volumes.
What types of parts are best suited for flattening?
Our hot flattening services are ideal for higher-volume production of flat components where consistency and repeatability are critical.
Ideal part characteristics include:
- Flat parts under ¼” thick (though dimensions can vary)
- Components up to 36″ in diameter
- Production quantities where systematic processing delivers efficiency
Common applications that are best suited for flattening:
- Cam phasers
- Automatic and manual transmission clutch components
- Tooling
- Brackets and spacers
- Metal stampings requiring precise fit or weld alignment
- Automotive seat assembly components
What's the difference between flattening and straightening?
While both processes correct warpage that occurs during heat treatment, they work differently. Straightening is a manual process where hydraulic presses are used to apply targeted pressure to specific areas of a part, carefully bending it back to specification. Parts must actually be bent past straight to spring back to the correct position when pressure is released.
Hot flattening (also called clamp and temper) is a more systematic process ideal for higher volumes of flat components. Parts are stacked between large flat plates, clamped together, and heated to relieve internal stresses. When unclamped, the parts retain their flat shape. This works particularly well for relatively thin, flat components like cam phasers, clutch components, brackets, and spacers under ¼” thick and up to 36″ in diameter.
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