Cold-forming is a high-speed metal-forming process where coiled wire at ambient temperature is precisely sheared to length, and then passed through a succession of tool and die cavities to displace the working metal.
Within a short period of time, a large number of cutoffs can either be upset, formed to be longer or shorter in length, or small amounts of material can be removed by trimming or piercing.
In this process, metal is forced beyond its yield (elastic) limit and retains its altered shape upon removal from the die. The metal should not be forced beyond its tensile strength, otherwise cracks would occur (the exception is when trimming or piercing).
Historically, cold-forming has been an experience-based technology, but this is changing as new computer-aided analytical tools are constantly being developed to facilitate efficient material processing.
Apart from large quantities due to the high production speed, forming to net/near-net shape is possible to eliminate or reduce secondary operations. Furthermore, the finely tuned machines allow for a high volume consistency, leading to material savings and reduced scrap volumes. The improvement in mechanical properties, e.g. greater strength-to-weight ratio, renders another positive effect.
Because of these benefits, cold-forming can be an interesting alternative to hot forging, casting, sintering, machining, welding or stamping.
Cold-forming equipment is typically a horizontal press. Machines come in many variations, with diverse criteria being important according to the type of parts to be produced. Materials that can be cold-formed include carbon steels, stainless steels, brass, copper, bronze, precious metals, aluminum and nickel alloys.
Cold-forming the chosen material into a given part shape is governed by that material's structural properties. They are all based on 3 basic forming methods:
• Forward extrusion reduces the diameter, with the material either being open or trapped to flow into the cavity of lesser diameter.
• Backward extrusion has the material flow backwards around a penetrating punch - a method to form hollow spaces.
• Upsetting is a method to form heads on fasteners, where material is upset at the face of dies (e.g. bolts).
Innovation and stability - for 140 years
Not many companies in the industry have such a long and eventful history as National Machinery. In the course of over 140 years now, National Machinery has lived through some turbulent times, from which the company always emerged stronger than before.
The foundations for the then-called National Machinery Company were laid in Cleveland, Ohio, in 1874. In the early 20th century, the company moved approx. 145 km southwest to Tiffin, and was received its accolade when the "New York Daily" called it a "mammoth concern", "being the only establishment in the world capable of equipping a bolt and nut factory with machinery".
For comparison: By 1902, the plant in Tiffin had expanded to 6,300m² - todays buildings cover an area of more than 55,000m².
The key to their success as a machine manufacturer was their unerringly watchful eye on the requirements of an ever-changing industry. The early 20th century was the era of a booming US automobile industry and full order books. Henry Ford was enthusiastic about the Automatic Tong Feed Forging Machine he had purchased from National in 1925.
Soon afterwards, however, a lot of stamina was called for in the recession of the 1930s. National Machinery had it and - despite the depression - threw new invention upon new invention onto the market, an investment that should prove worthwhile.
By the time the 1940s drew to a close, the company, thanks to its innovations (such as the famous High-Speed Forging Maxipres as well as various Boltmaker® and coldformer models including models for long-stroke parts) had been able to triple in size with now 500 employees earning their bread and butter at National. In the late 1950s, National entered the European market by taking over the Germany company J.G. Kayser, the largest manufacturer of cold forming equipment of the time outside the USA.
The 1960s carried an increasing demand for more complex-shaped parts. Even in Europe, National Machinery's market share was on the rise and thus the year 1972 saw the 1000th high-speed cold former ship from National's expanded Nuremberg facility. The company continued to write record order numbers well into the 1980s.
However, even National felt the effects of the global recession only shortly later. A gigantic increase in sales numbers was necessary in order to get the machine inventory on stock into the market and once again, innovation in coldforming technology turned out to be the key solution.
The FORMAX® concept
In 1989, National Machinery introduced its FORMAX® cold former for the first time at the International Fastener Exposition (IFE) in Atlanta, Georgia. FORMAX presented itself as an easy-to-operate system to the fastener and component industry that allowed for with high production speeds and simple and quick tool changes.
FORMAX®'s design was tailored to National Machinery's production capabilities in order to economize production processes and standardize components. This allows for close tolerance control and takes away the “hand fit” typically needed at assembly, so each machine is of the exact same high quality.
FORMAX® features a core design with standard machine options "on top" and is the perfect platform on which to mount flexible specials. FORMAX® machines can be adapted to changes in the customer's requirements.
There is also a special FORMAX® design for warm-forming machines. The warm-former models of the FORMAX® line have all of FORMAX®'s standard features such as zero-clearance heading slide guidance, linear feed system, sealed heading slide guide liners and the Quick-Change FORMAPAK System.
A FORMAX® warm-former machine may be either prepped for warm-forming - with basic special features - or it may be custom-tailored particularly for the application and material requirements of a certain customer.
For National Machinery, the FORMAX® line meant greater efficiency under production aspects, quicker production speeds and improved use of machine and tooling resources. The customers particularly benefitted from the improved quality and production speed.
The future goes global
Over the decades, National Machinery has manufactured thousands and thousands of headers which are still in operation in over 130 61 countries worldwide. Reliability and sturdiness remain National Machinery's core competencies.
From Nuremberg, Germany, NME National Machinery Europe GmbH offers machine service, new machine sales and technical support for their customers in Europe, Africa and the Middle East.
Nevertheless, apart from Canada, the USA and Brazil, NM machines are also located in the Far East. In 2007, National Machinery further expanded its presence around the globe by opening it's new subsidiary in China. NM Group Technologies resides on a 4,000 m2 premises in Suzhou, PRC – and supports China for sales and service.
National Machinery has a particularly large machine base in Japan, thus making their Nagoya, Japan facility indispensable especially for this crucial customer base in terms of quick and inexpensive deliveries service within Asia.
In December, 2015 National Machinery LLC announced that it had taken a controlling interest in SMART Machinery Srl. SMART Machinery is a new company formed to assume the business interests and assets of S.M.A.R.T Srl, the Tortona, Italy-based company that is a leading thread roller machine manufacturer and pioneer in using servo drive technology.
Using its patented technology, S.M.A.R.T. has developed a full range of flat die thread rolling equipment to serve the fastener industry. It also manufactures complementary equipment that includes planetary machines, washer assembly units, and pointing machines. Smart machines have been widely accepted by the market, and operate today in many countries.
National Machinery will become the global master agent for the sale and service of SMART equipment, using select sub-agents as well as company personnel. This addition to the National Machinery portfolio of products will give customers even more options of high quality, technologically advanced equipment for their production needs, and shows National’s commitment to the industry.