The value of vacuum PVD coating in medical instruments
Applying PVD coatings to medical devices can provide aesthetic and functional advantages. Here are some answers to common questions.
Physical vapor deposition (PVD) is a vacuum coating process that many people know is often used to improve the performance of cutting tools. However, the vacuum coating machine equipment of IKS PVD can provide the cathode arc PVD coating service to provide harder and more lubricating products, which can increase the tool life by 10 times compared with uncoated tools, wear resistant surface.
In addition, medical device manufacturers are increasingly using PVD coatings to distinguish the appearance of their devices from similar products and/or enhance the performance of their devices, as the rigid inert coating is biocompatible and does not react with bone, tissue or body fluids. Examples of medical devices coated with PVD include jammers, drills and needles, as well as "worn" parts for various device components and dental applications.
PVD coatings provide better edge retention, so the surgical instruments remain clear. For other equipment, they reduce wear between mating stainless steel components and help prevent oxidation and corrosion.
Common problems with PVD coatings:
What is the cathode arc PVD process?
Cathode arc PVD is the process of using an arc welding machine to vaporize various metals from the solid source material in the vacuum chamber. Vaporized metals such as titanium, chromium, zirconium, aluminum and various other alloys react with gases (usually nitrogen and/or carbon containing gases) to form a coating material that condenses on the coated parts.
The cathode arc PVD produces a high level of metal ionization (over 95%), which helps ensure a high coating adherence to the substrate material. The method usually has a wide operating window, which makes it possible to deposit high quality coating with various process parameters. Other coating processes, such as sputtering or ion plating, are less robust and have smaller operating Windows, making it more difficult to consistently produce high-quality coatings.
What preparation should be done before painting?
In order to obtain a good adhesive coating, the parts to be coated are very important to clean. The surface of the part must be free of oxides, EDM recasting and organic films, as these contaminants can adversely affect the coating quality.
To remove contaminants before coating, coating companies use techniques such as polishing, tumbling, acid etching and sand and glass bead spraying. However, some of these technologies can change the surface finish of the coated parts, so PVD coating companies often work with customers to develop processes that meet their requirements for coating quality and part appearance.
Will the coating process adversely affect the sharp edges?
If the part has a sharp edge, the cleaning process that may adversely affect edge clarity will not be used. In addition, coating processes can be modified to reduce heating and coating rates if the coating is small or very fragile. These improvements ensure that the delicate features do not overheat and that the coating is not too thick.
What surface treatment is most effective?
The PVD coating is very thin (typically 0.0001 to 0.0005 inches) and usually replicates the original surface of the part (unless using abrasive cleaning processes). The best results are obtained when the surface of the part is smooth. As a result, grinding or polishing surfaces usually produces better results than sandblasting or matte surface treatment.
It is best to allow the applicator to create a texture on the part if a matte finish is needed in a specific area of the part. Part supplier textures may contaminate this area of the part, which requires some rework, negating any savings that the supplier may rely on.
How much temperature is used in the PVD coating process?
All typical coating surface treatment of PVD coating temperature is about 800 ° F. The coating temperature changes the hardness of the parts or causes the parts to deform (shrink or grow). In order to minimize the possible impact, we proposed to heat sensitive components from 900 to 900 ° F temperature tempering processing, then coating processing.
What types of materials can be applied?
PVD coating can be applied to most of the metal to withstand heated to 800 ° F. Commonly used medical materials include 303,440C and 17-4 stainless steel; Titanium alloy; And some tool steel. PVD coatings are generally not suitable for aluminum because the coating process is at temperatures close to the melting point of the material.
What coatings are commonly used for medical devices?
Medical devices are usually four PVD coatings. The most commonly used are titanium nitride (TiN) with a thickness range of 0.0001 to 0.0002 inches, vickers hardness range of 2,400 to 2,600Hv, and gold.
The second most common medical coating is aluminum titanium nitride (AlTiN), commonly known as black nitride or black titanium coating. It has a thickness range of 0.0001 to 0.0002 inches, a hardness range of 4,000 to 4,200 Hv, and a carbon black surface.
The other two medical coatings are chromium nitride (CrN) and Alpha. The thickness range of CrN is 0.0001 to 0.0005 inches, hardness range is 2,200 to 2,400Hv, and silver surface treatment. Alpha is a multilayer coating that has a top layer of zirconium nitride (ZrN) and produces silver-gold. Its thickness ranges from 0.0001 to 0.0002 inches, with maximum hardness, ranging from 4,400 to 4,600 Hv. Due to its higher hardness, lubricity and wear resistance, the coating can be two to four times longer than TiN.
What are the advantages of PVD over chemical vapor deposition (CVD) coating processes?
PVD coatings are coated at a much lower temperature than CVD coatings, and PVD coated parts do not have to be heat treated again after coating. In addition, PVD replicates the surface finish on the part, while the CVD coating produces a lackluster finish unless the part is polished after coating.
What are the advantages of PVD over anodization?
Coated with a titanium alloy, PVD is more wear-resistant than anodization and keeps its color better over time.
In addition to medical devices and cutting tools, PVD coating is often used to improve the performance and service life of stamping tools, molding tools and injection molding wear parts.
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