WINTER 2023

14 THE DISTRIBUTOR’S

14 THE DISTRIBUTOR’S LINK Bruno Marbacher Bruno Marbacher earned his mechanical engineering degree in Switzerland, he also holds a business degree. He started out as a tool and die maker (poly-mechanic) and over the years he has held various management positions in quality and engineering. During his time in America he has developed and given numerous seminars on topics related to the proper use of mechanical fasteners and machine elements, and assists engineers in solving fastening/assembly issues. His has groomed and directed many young engineers in fastening/assembly technology. He now offers his 40 years of experience through writing and lecturing. THREAD FORMING SCREWS FOR COST-EFFICIENT FASTENING IN METAL AND PLASTIC Dear Reader, With this article, I will start a series of articles about thread forming (thread shaping) screws for metal and plastics. Numerous articles have been written about thread forming screws, but you may still learn from the information I am about to present. Thread Forming Screws As the name implies, thread forming screws form their own mating thread, no need for tapping the mating thread. Internal threads are either cut or cold-formed. They tap their own hole as they are driven into the material. More narrowly, self-tapping is used only to describe a specific type of thread-forming screw. They are intended to produce a thread in relatively soft material or sheet materials, excluding wood. Other specific types of self-tapping screw include self-drilling TECHNICAL ARTICLE screws and thread rolling screws. A great number of thread forming screws have been developed over the years some of them are rarely used anymore or are only used for niche applications. Usually, thread forming screws are tapping screws for sheet metal, thread forming screws for steel and aluminum plates and thread forming screws for plastics etc. Since each screw produces its own mating thread, there are no problems with thread tolerances. The screws sit play-free in their mating threads and thus they have an excellent vibration resistance. The forming of threads produces a certain resistance. Most thread forming screws cannot be installed with hand tools they more often than not require power screwdrivers. The fact that these screws are very reliable and safe and eliminate several operations, related to assembly, makes such screws very cost-efficient. They should be used in place of regular screws whenever possible. Tapping Screws, The Original Thread Forming Screws Tapping screws were developed in England. They are sometimes called sheet metal or P-K screws from the brand name Parker Kalon. Parker Kalon pioneered the manufacture of, but did not invent, these screws. Tapping screws were the first fasteners that were forming their own mating thread into sheet metal. No chips are produced during assembly. CONTINUED ON PAGE 100