In today's global market, delivery, quality and cost have replaced convenience of location as determining factors in corporate working relationships. With the advent of overnight shipping and communication via the Internet, competition worldwide is growing more fierce everyday. This is the case with microscopic welding. The company that a moldmaker chooses as its welding source for its production/repair team can mean the difference between downtime of five hours or five days.
In the past, welding was feared by most toolmakers. Many reputable manufacturers even adopted a "no weld uot; policy on new molds. This was due, in part, to early welding methods. When welding became a viable option in mold manufacturing and repair, nobody had heard of welding under a microscope, tiny diameter wire or low amperage. Welding helmets, large diameter welding rods, inaccurate preheating and bad technique were common. This resulted in large welds with cracks, pits and unacceptable sink, as well as welds that would often crack off of the piece down the road.
Cosmetics also were an issue. It was embarrassing to introduce a customer to his/her new mold with big, ugly, black-and-blue weld spots on it. Therefore, weld was held to a bare minimum - becoming a last resort only to be used if one had to squeeze a few additional shots out of an ailing mold. Now, with additional experience and advancements in technology during the past 20 years, microwelding has emerged as an integral component to mold repair and manufacturing.
Many moldmaking facilities still are not aware of the capability of an elite or "micro-dimensional" welder. Are there cost saving advantages to using such a source? The following will attempt to answer this question. Whether it's mold production, mold repair, rapid prototyping, design changes, the complex oxygen tubing in the space shuttle helmets or the ultra-sensitive medical field, micro-dimensional welding is being used by many pioneering industries and is proving to be a tremendous new tool in redefining manufacturing and repair processes.
What is a Micro-Dimensional Welder?
What is a class A or "micro-dimensional" welder? He/she is one who can place and form weld in complex shapes and sizes within specified tolerances like a moldmaker - with the ability to prevent, control and eliminate distortion caused by the welding process.
Typical tolerances for a true micro-dimensional welder are usually +/- .002" in X and Y dimensions and +/- .005" in the Z dimension. The ability to do this in hard-to-reach areas, on thin blades or in other adverse conditions is a skill which only a select few have attained. Far more than a low-amp welder, a .003"-diameter welding rod and a microscope is needed. Anyone who has attempted microwelding or who uses such a source can attest to the unavoidable need of many devoted and costly years of experience. Simply investing in equipment and recruiting a part-time, in-house welder yields mediocre welds at best and the results are compromising to the metal's integrity and the longevity of the welded component.
Many "quick fix"-type alternatives - such as paste or ribbon welders - have evolved in recent years, but fall short of the quality and speed of a micro-dimensional welder. Necessary traits for a micro-dimensional welder include manual dexterity, patience, creativity, surgeon-like steadiness and an artistic ability to visualize and create complex, 3-D geometric shapes. Also, a close tungsten arc gap of .002" or less while welding in critical areas, which is a must in small, hard-to-reach and/or highly-detailed areas. A background in moldmaking, mold design and metallurgical knowledge also is necessary to fully understand and apply the most cost-effective welding solution.
A full-service micro-dimensional welder, like other businesses, needs to use certain professions fully in order to serve its customer's moldmaking team effectively. The ability to intelligently communicate with full knowledge of moldmaking, mold design and molding is a must in order for the welding house to accurately evaluate where weld is needed and why. Same-day shipment as well as adequate personnel to initiate a job upon arrival can mean the difference between a delivery in hours or days. The ability to speedily analyze issues and/or recommend alternatives to welding also can save the moldmaker a lot of wasted time. These combined ingredients yield tremendous immediate and long-term cost savings.
Inside of the weld house, advanced education and experience of the metallurgical effects of heat have evolved into weld, which in some cases actually outlasts the component to which it was applied. Experience with common tool steels (S-7, 420 SS, H-13, P-20, etc.), problematic tool steels (A-10, D2, 440 C, etc.), non-ferrous metals and a regimented program for updating knowledge on new materials is a necessity. Knowledge of the effects of pre- and post-heating the materials on an individual basis is another necessity. Variations in these processes may have dramatic effects on weld longevity and stresses to the welded piece. A full-service weld house also should have some machine shop capabilities for the production of fixtures, jigs and components - as well as a quality control department to monitor weld sink and thermal distortion.
Evolution of the Micro-Dimensional Welder
While only a handful of elite, micro-dimensional welders worldwide have brought welding to such a level, those companies that utilize them rarely go back their previous source. Experience, technological advancements and especially technique have led to micro-dimensional welders being able to deal with various plating types, nitriding and other surface treatments. Even high-polished and textured surfaces can be duplicated after welding - yielding results, which satisfy even the most demanding moldmakers.
In addition, some facilities offer microscopic refinishing and texturing services. Oftentimes, for small cosmetic repairs, a true micro-dimensional welder can apply weld accurately and sparingly enough to only need re-finishing by hand. This can eliminate costly setup time. Techniques to minimize or eliminate sink also have been developed. A few elite welders are actually able to create "negative sink," or raised steel around the welded area, which after refinishing is in most cases undetectable.
With the combination of expertise and knowledge of a micro-dimensional welder, weld can be placed where and only where you want it, with its size and shape being maintained within specified tolerances. This means less downtime and less re-machining, which frees up a moldmaker to concentrate on his/her other functions.
Another recently developed ability of some micro-dimensional welders is to maintain and actually re-establish straightness and flatness of geometrically-challenged components. Although those who have harnessed this ability seem reluctant to share their methodology, components can actually be returned straighter and flatter than when they were shipped! The benefits of such a service are obvious.
Applications and Techniques
With such advancements and true maintenance of steel integrity, some manufacturers are taking advantage of these abilities in their design and manufacturing processes. Large, flat surfaces with protruding features do not always need to be inserted or machined around, which takes more time. Due to advanced techniques, surfaces can be finished with the feature actually being formed with weld afterward on the finished surface. This process can eliminate the EDMing or milling of insert pockets, reduce programming time and a host of other processes.
An additional example is that some organizations have streamlined their insert production by wire EDMing insert profiles to finished dimensions - saving milling and grinding time - and simply welding on the "heel" afterward! Also, gate and high-wear areas are being added in after heat treating for increased Rockwell, wear resistance, etc. Such practices have proven time-effective in rapid prototyping, where welding can eliminate weeks of unneeded work. Truly, the age of components being made of a single material has become a thing of the past. Cracks, voids and sinks also are avoidable, making micro-dimensional welding a genuine advantage.
In short, welding is no longer a barbaric, last-ditch solution to repair or modify a mold component. It has become a highly technical, proven process. With the ability for decreased downtime, increased tool life and enormous time-saving potential, micro-dimensional welding is becoming the competitive advantage that puts some manufacturers ahead of their competition.