| Business | Phone |
| American Heat Treat Furnaces 9710 W Flagg Ave, Milwaukee 53225 | (414) 527-9055 |
| Commercial Heat Treating Inc 1952 S 1st St, Milwaukee 53204 | (414) 383-0139 |
| Cooperheat-Mqs Inc 5512 W State St, Milwaukee 53208 | (414) 771-3060 |
| Fpm/Milwaukee 11200 W Heather Ave, Milwaukee 53224 | (414) 355-7900 |
| Furnace Control Corp 5610 W Florist Ave, Milwaukee 53218 | (414) 462-7575 |
| Heat Treating Engineers Inc 1146 N 54th St, Milwaukee 53208 | (414) 258-1484 |
| Wisconsin Steel Industries Inc 1225 S 41st St, Milwaukee 53215 | (414) 645-2340 |
| Treat All Metals Inc 5140 N Port Washington Rd, Milwaukee 53217 | (414) 962-2500 |
| Tenaxol Inc 5801 W National Ave, Milwaukee 53214 | (414) 476-1400 |
| Service Continuous Inc 10536 W Glenbrook Ct, Milwaukee 53224 | (414) 355-5353 |
| Service Heat Treating Inc 9320 N 107th St, Milwaukee 53224 | (414) 355-1020 |
| Racine Heat Treating Co Inc Milwaukee 53202 | (414) 271-8797 |