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IMTECH of California Service Center - Santa Fe Springs, CA
- Impregnating of
Micro-Cracked Nickel Chrome
- Cleaning and Degreasing
- Certified Pressure Testing
- KleenPartz Kontainer Program
- Rapid Prototype Parts Impregnation
IMTECH, Inc. located at 8424 Secura Way, Santa Fe Springs, California 90670, opened in 1986 to service the porosity sealing needs of many southwest manufacturers. Here our impregnation job shop processes customer's parts to seal porosity on a contract basis. Using the MIL I 17563C approved material, Impco's RC 80, Imtech specializes in solving problems created by porosity in multiple substrates, especially ferrous and non-ferrous castings, powder metal, ceramic, and other parts through impregnation. Because of the large size of our equipment, we are able to handle many different size parts such as housings, molds, and pumps. Similarly, the larger equipment allows us to continuously service our customers who have long production runs on a timely quick-turn basis.
An Impco Kleenpartz degreaser co-located at Imtech provides airless vapor degreasing services for customers with demanding cleanliness and pressure tight requirements.
Our leak testing services allow for complete testing and certification of customers parts with full documentation provided.
Imtech's highly skilled technical staff specializes in processing hard to seal porosity. Our years of experience and unique methods combined with our quality control provide you with leak tight and clean parts.
Whether it is impregnation sealing services or any one of our other special services such as pressure testing, sealing very large castings, sealing gross porosity using our Imseal-800, parts cleaning utilizing our airless high vacuum vapor degreaser, or anodizing, Imtech is ready to solve your sealing problems quickly and efficiently.
Black is Black and it is a difficult color, especially on castings. Introducing Imtech's newest service: Anodizing. What makes this different and unique is that we specialized in anodizing castings, and as a result we get exceptional quality and uniformity in both Clear and Black anodize.
For anodizing, castings present unique challenges. For one, the base-casting alloy contains many elements that negatively impact anodic coating quality, especially Copper. Many aluminum casting alloys contain 2% and more of copper. For another, castings are irregular in form requiring special attention to rack orientation and design to allow proper drainage and prevent water marks on the surface. Lastly, surface cleanliness is paramount. Without a clean and uniformly reactive surface, an anodized casting appears "splotchy" or "smutty" and its color is uneven.
Imtech's newly installed anodize line addresses all these important issues and more. We have been dealing with casting alloys for over 60+ years and understand their chemistry and metallurgy. Casting orientation and racking is in our blood. Without it, casting blind holes would be filled, watermarks would abound and the impregnation process itself would result in more rejects for poor quality and problems created than for leakers. Finally, castings that go through the impregnation process and move to anodizing have an surface that is not only extraordinarily clean, but passivized as well resulting in a uniformity of coating that is unmatched.
A well-known problem with castings is porosity. Porosity leakages is the main reason that casting are impregnated, to make an otherwise sound casting, which leaks, leak â€“free and fully functional. In anodizing, especially black anodizing, porosity also plays an important role. Anodic coatings form at the surface of the casting through a conversion process involving electricity. The thickness of the coating is generally a function of immersion time and current flow, with surface configuration playing an important role in coating formation. Too thin and the coating doesn't provide the required protection. Too thick, and the anodize coating physical properties change from an ultra-hard surface to one that is soft and chalky.
Irregular surface geometry causes portions of the casting to be a different distance from the cathode, thus slowing the formation of the anodic coating in some area and speeding it in others. To compensate, the bath immersion time is generally increased. Porosity in a casting acts just like the irregular surface of a die cast part. On a micro scale, the pore is the irregularity, and is further away from the current flow. Increasing the time improves the anodic coating in the pore, but runs the risk of causing the surface coat becoming thick and soft. By impregnating the part prior to anodizing, the pores are closed and the coating build is more uniform.
Back to the black. In the subsequent coloring step, the anodic coating's porosity is dyed. If the coating density varies, the dye and the sealer absorb at different rates, resulting in a mottled or smutty surface one which literally rubs off on any surface. As mentioned above, impregnation fills the pores and helps make the anodic coating more uniform. However, for black, a more insidious defect occurs: Freckles.
Freckles appear on black anodize surfaces soon after the anodized part is sealed and dried, and generally come in two forms, small white mounds on the surface, or silver dots in the dyed coating when the casting is inspected under natural light. In both cases, the defect's root is a pore, but its causes are different. The white mound is the result of corrosion, generally when the anodize electrolyte is not completely removed from the pore during the rinse process. Due to capillary forces, the acid remains at the base of the pore because the rinse step was insufficient. The trapped electrolyte prevents the black dye from entering the pore and the raw anodize surface cannot be sealed because the sealer cannot penetrate the electrolyte to do its job. Over time, the acid electrolyte continues to promote oxidization and the white mound appears.
Dots or specs are more difficult. When these appear, it is generally the result of ultra fine porosity not trapping the electrolyte, but actually preventing the electrolyte from reaching the casting surface and promoting the conversion process. In this instance, the surface tension of the acid bath is so great (even above that of water at 72 dynes/cmÂ²) that it cannot enter the smallest of the pores. Since there is no conversion, subsequent dying is ineffective and a minute discolored spot appears, which becomes all the more discernable against the black background.
In both of these cases, impregnation improves the anodizing result. Where there is larger porosity, impregnation seals the depths of the pores and prevents the entrapment of the electrolyte and the subsequent oxidization. Where the porosity is ultra fine, the combination of the low surface tension of the impregnation resin (less than 28 dynes/cmÂ²) and the pressure used (100 psi or 6.9 bars) to force the impregnant into the pores, seals the pores and provides a bridging base for the conversion coat and dying process to assist in giving a uniform color.
Which comes first: Anodize or Impregnation?
Over the years, there has been a great deal of debate over which process should come first, anodizing or impregnation. The arguments on both sides are well known. Those who state that the anodize should come first point to the fact that the impregnant is generally a thermoset plastic and a conversion coating of anodizing on a plastic surface is not possible. From the impregnators point of view, since the anodic coating generally adds some small dimension to the part surface, it was felt that this could close some of the finer porosity and make sealing more difficult. In general, from the specification point of view, there is no preference, with the controlling MIL STD 276A allowing anodizing either before or after impregnation.
- From Imtech's point of view, the answer is clear: Anodize after impregnation and for the following reasons:As we outlined before, impregnation leaves a clean and somewhat passivized surface on the casting. This allows for a more uniform conversion coating and better, more uniform color.
- Impregnation reduces the likelihood of an irregular surface that could ultimately cause the anodize coating to be less hard and more irregular.
- On colored parts, impregnation fills the smallest porosity and prevents the thinning of the coating and fading of the color.
- By impregnating before anodize, the likelihood of a scuffed, scratched or dinged surface is reduced because there is no parts handling to re-rack parts for the next process.
The Importance of 1
Of all the things that are important, it is the overall delivery of service to the customer. Prior to Imtech's addition of anodizing, customers had to two steps to complete their casting finishing: first send their parts to us for impregnation, have them returned and then send their parts to the anodizer, and wait for their return. Realistically, total elapsed time was between 2-3 weeks. Now it is one week, and the value is obvious:
- One Responsibility
- One purchase decision
- One week
- One call or email
The value of ONE.