What’s Special About Special Processes?

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Dry Film Lubrication

Dry Film Lubrication

Any process that could change or alter a parts material or physical integrity by introducing stresses with mechanical, thermal, or chemical operations may be considered a Special Process. In most cases Special Processes are controlled by the OEM’s and you must validate the special process in order to ensure there are no deficiencies as a result of the Special Process. In many instances, special processes are those that your organization is unable or unwilling to do yourself.

The need for accreditation of manufacturing processes is most obvious in the aerospace industry, where there exists an industry-managed program for quality systems and Special Processes called Nadcap (National Aerospace and Defense Contractors Accreditation Program). Nadcap auditors are required to be experts in the particular Special Processes they audit.

Before a Nadcap Special Process audit can be conducted, your quality system must be certified to AS9100, AC7004, or equivalent. Nadcap uses prime and industry standards of conformity in Special Processes. For a company’s Special Process to meet Nadcap accreditation, specialized Nadcap audits for individual processes are required.

Pre-Bond Priming

Pre-Bond Priming

Nadcap accreditation in Special Processes is a mandatory requirement if you are a supplier for General Electric, Boeing, Airbus, Honeywell, Rolls Royce, Sikorsky, and many others. Nadcap accreditation is based on Special Processes used by aerospace suppliers such as:

  • Dow Coatings on Magnesium
  • Dry Film Lubrication/Anti Gall
  • Passivation
  • Nondestructive Testing methods
    • Magnetic Particle & Dye Penetrant Inspection
  • Millipore®/Precision Cleaning
  • Shot Peening
  • Adhesive Bonding

Special Processes involve extensive, criteria-specific practices and require qualified personnel, approved equipment, and verification of defined procedures.

Subcontracting your Special Processes gives you the freedom to continue manufacturing quality parts without costly additions to your operation. You get the benefits of delivering industry-approved product while saving money, reducing lead times, and focusing on what you do best.

The Benefits of Adhesive Bonding

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Bonding&DFL._cropAdhesives are the number one choice for joining methods. Because of its numerous benefits, adhesive bonding is used in many different industries, and when compared to the alternative of welding and riveting, adhesives win by a landslide.

Loctite’s post “Adhesives are not second best” describes in detail the many benefits of adhesive bonding over mechanical methods of joining substrates. Loctite, a German manufacturer of high-performance industrial adhesives and sealants, explains the difficulties of traditional bonding techniques
and how adhesive bonding gives you improved performance.

Loctite outlines adhesive bonding benefits, including:

  • Less corrosion and material fatigue
  • No heat distortion or warping
  • No weakening
  • Greater flexibility for use with dissimilar materials
  • Increased rigidity and stiffness
  • Decreased weight
  • Cost savings in workforce training and inventory
  • Improved cosmetic appearance

Although there are many circumstances where welding and riveting are appropriate, any limitations are easy to overcome with adhesives. “Adhesives are certainly not second best when it comes to the selection of joining methods. Indeed for many engineers, adhesives are the first – often, the only – choice,” Loctite said.

When choosing the right adhesive for your parts, it is important to understand the different application benefits and adhesion properties. At PTI Industries, we help you find the right adhesive, because, as Loctite says, “there is no such thing as the totally universal glue.”

Adhesive bonding is a high-tech service PTI Industries offers as one of our many specialized processes, giving you a one-stop experience for your critical part processes.

For additional information check out our blog from July 2014; The 10 Top Things to Look for in an Adhesive Bonding Company.

Inside PTI’s Precision Cleaning Room

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Our Clean Department Crew

Our Clean Department Crew

Your sensitive parts demand specific precision cleaning requirements that can involve widely different cleaning methods. Inside PTI’s precision cleaning room you’ll find areas designated for many different cleanliness levels and processes.

Within the clean room a department manager oversees two supervisors, technicians, engineers, and processing employees, each assigned to maintaining conformance in the various precision cleaning methods. From your initial job request to your part’s final on-time delivery, a member of our team follows your part through all stages of the precision cleaning process.

A technical group leader is responsible for your part, staying actively involved in the job until your part is processed to meet all requirements in a timely fashion, even if this means running the process multiple times.

Each precision cleaning team member receives multiple layers of training, first on the equipment and its setting up and use, and for the particular parts assigned to them. Each part undergoes thorough evaluation from our technical quoting group, who receives a new part’s specifications and information from the sales department that takes your order.

From the initial visual verification inspection under white or black light, most parts will then undergo a wide variety of possible testing ranging from the visual to particle weight and size. The equipment also meets rigorous testing to assure it’s free of the same size particles.

Each part sent into the clean room is cleaned according to its recommended method, with different cleaning methods applied to a single part without leaving the confines of the clean room. This ensures that your part’s cleanliness is preserved and remains in conformance to industry and contract standards

Our precision cleaning and cleanliness testing equipment and capabilities include ultrasonic cleaning, CO2 snowgun, vapor degreasing, media blasting, aqueous immersion, turbulent flushing, and high pressure spray room washing. The list of certifications and specialized process approvals are designed to comply with industry specifications and very strict cleanliness standards.

Your part receives the highest levels of cleanliness through PTI’s numerous clean room processes. Our in-process cleaning methods have grown out of the need to meet your precision cleaning requirements.

Your end-cleaned product for all the industries we serve, including the aerospace, medical, automotive, and laser industries, will show superior performance and endurance, reducing OEM warranty claims.

Give us a call with any precision cleaning questions you have and learn how PTI can assist you.

A Case Study in Part Cleanliness

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152494710Recently on several precision cleaning jobs we were unable to meet the cleanliness requirements on anodized aluminum* parts that contained internal passageways. Regardless of how many times we cleaned and tested the parts, a never-ending stream of small aluminum chips kept showing up in the test samples.

After close study, we discovered that the parts had not been cleaned prior to being sent to the anodize vendor. During the anodize process, machining chips became adhered to the sides of the internal passages, which started flaking off randomly during precision cleaning.

Most aircraft engine specifications require the machining house to perform “In-Process Cleaning”, also known as “clean as you go”, to prevent this kind of situation. Precision cleaning is not designed to remove gross manufacturing debris.

Over the years, we’ve learned that obtaining a “good, clean” anodized part requires thorough cleaning prior to the anodize process. This is especially true for components that have internal passageways, including intersecting cross drills and inaccessible recesses.

A contributing factor is that many of the aqueous based coolants in use today tend to evaporate quickly and form a sticky residue that is infamous for entrapping machining chips and locking them onto the surface of the part. These particles stick to the surface and insulate it from the electrolyte fluid and the electrolytic action actually “burns and locks” the chips onto the surface of the part. Depending on how tightly they adhered to the surface by the anodize process, it’s nearly impossible to remove them during precision cleaning.

To prevent this from happening, the parts must be cleaned immediately after each machining operation to remove coolant and chips before the coolant can coagulate and entomb the chips in the part. Exotic methods are not required for an effective job of removing coolant and chips.

For aqueous based coolants, simply flush the passages with water and follow by drying with water/oil/particle-free shop air. It is always a good practice to start flushing the smallest holes first and work up to the largest, preventing chips from becoming lodged in restriction points.

As Benjamin Franklin said, “An ounce of prevention is worth a pound of cure.”

For more information on effective flushing techniques, call Chuck Osborn at 860-698-9266, or email him @cosborn@ptiindustries.com.

* The same holds true for components of any alloy with internal passageways.

Dow Coatings for Your Magnesium Components

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airplane_wheel_ptiBecause it is one of the lightest and strongest metals available, the use of magnesium is growing in many industries including aerospace, automotive, electrical and military. It has good fatigue strength, excellent strength-to-weight ratio, is non-magnetic and has relatively high thermal and electrical conductivities.   The disadvantages of magnesium is that is has poor corrosion resistance properties which can lead to structural or mechanical failure and has inadequate adhesion qualities for paint.

Like most metals, magnesium will oxidize when exposed to the atmosphere and exposure to water or high humidity causes it to corrode even more rapidly. To ensure safe and reliable performance, magnesium components must have some form of protective treatment.

Protective coatings are applied to magnesium parts to slow corrosion and ensure long term structural integrity. PTI offers three types of magnesium coatings:

  • Dow 17 Anodizing
  • Dow 7 Chemical Conversion
  • Dow 19 Chromic Acid.

Dow 17 Magnesium Anodize

This anodic chemical treatment is applied using an electrical current and is suitable for any magnesium alloy. The most robust of the three treatments, Dow 17 penetrates the surface and has a dimensional build up of between .0006 – .0012” depending on the thickness of the coating. The Dow 17 process results in a light green to dark green surface finish. It provides increased abrasion and corrosion resistance and is an excellent base for paint or any other post treatments.

Dow 7 Chemical Conversion Coatings

Dow 7 is a chemical conversion coating that is ideal for both new and overhauled parts that possess dissimilar materials such as inserts. The chemicals will react only to the bare magnesium converting the outer layer of the magnesium to a protective coating. This treatment has no appreciable dimensional change making it a good choice for parts with no coating tolerance. Dow 7 results in a brassy or dark brown finish depending on the type of magnesium alloy as well as the age and condition of the component.

Dow 19 Chromic Acid Coating

Dow 19 is used on magnesium parts that need a spot touch-up for minor damage repair or a temporary coating for corrosion prevention between production processes. This chromic acid coating is applied by manual application or immersion in a tank. Parts will be a light, brassy brown color varying slightly based on the type of alloy. Dow 19 also offers no appreciable change in dimension to the component.

PTI has been helping manufacturers with their magnesium components for over 30 years. Our dedicated and experienced technicians can help you determine which magnesium coating method is right for your components.

What is Precision Cleaning?

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MicroscopePhoto1Precision cleaning is required for any industry where stringent cleaning is vital for reliable and trouble-free performance of equipment. It’s commonly associated for use with aerospace components and medical devices, but other industries also must use precision cleaning methods.

Other applications that require precision cleaning is include laser components, heat exchangers, and cleaning for oxygen delivery services, all critical systems whose parts must undergo strict cleaning processes prior to use.

Failure to meet stringent precision cleaning requirements can have catastrophic results. Aerospace landing gear parts can fracture, oxygen delivery medical systems can transmit infection and spread disease, and laser components can malfunction and fail when improperly cleaned.

Specialized precision cleaning equipment is used to thoroughly clean contaminants such as soils, oxides, oils, metallic residue, and even dust from the surface of a substrate, or the base material of a part.

Selecting the right method of precision cleaning depends on the different type of contaminants and the type of parts that need cleaning. Careful testing of a part for accurate selection of a precision cleaning method is important to assure compatibility with your parts and the high-performance you require from your precision cleaned parts.

Finding a certified shop for your precision cleaning provides tremendous cost savings. You avoid paying for expensive equipment, complying with strict environmental regulations, and training and certifying your staff.

For optimum service and flexibility, a one-stop shop should meet your high-performance requirements of precision cleaning with multiple cleaning methods and accompanying certifications and approvals.

PTI Industries offers you the essential methods of precision cleaning for a wide range of high-standard cleaning applications.

Our methods of Precision Cleaning include:

  1. Ultrasonic
  2. Aqueous Immersion
  3. CO2 SnoGun
  4. Turbulent Flushing
  5. Vapor Degreasing
  6. High Pressure Spray Washing
  7. Media Blasting
  8. Cleanliness Testing

Applications requiring Precision Cleaning:

  • Cleaning of lasers
  • Aerospace parts
  • Medical devices
  • Low-volume, large auto parts
  • Off-road equipment parts
  • Semiconductors
  • Heat exchangers
  • Oxygen delivery services

Save time and eliminate potentially damaging results by calling us at 860-698-9266. Together we can determine and address your precision cleaning needs.

Passivation of Stainless Steel

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How It Works

Passivation ImageBy adding chromium to steel, a new breed of “stain-less” steel was born over a century ago. The added chromium combines with oxygen in the atmosphere and forms an invisible layer called passive film, making the steel resistant to rust.

A clean, freshly machined and polished stainless steel part will naturally acquire this protective film. However, this little miracle of chromium and oxygen atoms working together to protect steel from corrosion has limitations.

When stainless steel parts are fabricated by cold forming or machining, contaminants are introduced. Your shop floor, despite your stringent cleaning standards, has small particles of iron-containing dirt from cutting tools that can stick to the surface of stainless steel. Well-kept shop tools also contain corrosive-inducing steel which can adhere to your stainless steel parts.

Besides physical abrasion, surface damage is also caused by chemical reactions and expansion and contraction from heating and cooling processes. Rusting will result if the damage happens faster than the passive layer can naturally reform.

If the surface damage isn’t repaired and the foreign particles aren’t removed, a corrosive attack can start. It’s an insidious process that goes undetected to the human eye, but can eventually lead to rusting.

How to Protect Your Stainless Steel Parts

Passivation is a chemical process that protects your stainless steel by applying an acid and forcing the conversion of a uniform protective oxide layer, maximizing the corrosion resistance that steel already has.

This chemical treatment of a mild oxidant or acid must follow a cleaning process that removes oil, grease, and other residue left behind from fabrication and machining. Once the cleaning is complete, the acid is applied to the surface to enhance the spontaneous formation of the protective passive film.

Two types of acids are used to regenerate the passive layer. Both nitric acid and citric acid will effectively remove iron and its compounds from the surface.

Nitric acid is the most common method for passivation and is widely used for aerospace industry parts. It quickly dissolves all iron compounds and other trace metals on the surface of the stainless steel, regenerating the chromium oxide layer at the same time. Nitric acid requires high temperatures and an extended application time.

Citric acid is a safer and more environmentally friendly option that is effectively used for parts in the medical device industry. Because it’s not an oxidizer, citric acid relies on natural air oxidation to build up the corrosion protective layer.

The method of passivation you choose depends on the type of stainless steel. Both methods should only be performed by trained and experienced technicians who understand the safety practices and potential hazards.

PTI Industries complies with all industry standards, including EPA requirements for the necessary air and water permits and treatment capabilities. Specifications and verification testing are another critical component of passivation.

If you have any questions on passivation, give us a call at 1-800-318-8438. We will be happy to help you find the solutions you need to protect your stainless steel parts.

Top 10 Things to Look for in an Adhesive Bonding Company

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PTI Industries bonded the Rulon to the inner diameter of this aluminum bearing then machined the Rulon to dimension as well as blended the ends for a nice radius lead in.

PTI Industries bonded the Rulon to the inner diameter of this aluminum bearing then machined the Rulon to dimension as well as blended the ends for a nice radius lead in.

In our last post we defined adhesive bonding, discussed its advantages, how it’s evolved, and four things you should know about PTI Industries’ adhesive bonding service. In addition, there are other details you need to know prior to choosing adhesive bonding.

What types of materials can be bonded?

The types of materials you can bond are as varied as the production processes used. Adhesive bonding can be used to bond virtually any combination of materials with each other, provided you know how to prep the materials, eliminating the need for traditional joining methods.

Why choose adhesive bonding over traditional joining methods?

Adhesive bonding is the ideal way to join components or materials that don’t always work well with traditional bonding methods, such as welds, rivets, and screws.

Adhesive bonding’s advanced adhesive system gives you significantly stronger joints that are cleaner, lighter, and exhibit greater uniformity in the distribution of stress factors. Adhesive bonding eliminates the need for the high heat input and resulting damage often associated with thermal joining methods.

10 Things to Look for in an Adhesive Bonding Company

  1. Does the company keep adhesives in stock? Are they certified and controlled?
  2. If the adhesive you need is not in stock, what is the lead time for ordering?
  3. What is the shelf life of the adhesive?
  4. Is the company certified to perform the bonding process you need, and can they provide you with the written approval?
  5. Do they make their own fixtures/tooling, or will you need to provide this?
  6. What kind of quality system is in place?
  7. What is the optimal lot size for your part to get the optimal production rate?
  8. Do they issue a certificate of conformance once the job is completed?
  9. Do they need a sample or scrap part to develop the process or bond fixtures/tooling?
  10. Are there any additional testing fees that you will incur, such as for adhesive testing?

Additional Tips

  • Be sure to provide them with a print and all requirements that you will need and get a quote ahead of time…many times the bonding operation cost and lead time is underestimated.
  • What are the details needed for the bonding project? For example if you need a Teflon strip bonded on a metal substrate, many times the bond house will supply the Teflon. Determine in advance if you need to provide materials or if the bond house will supply them.

Before you choose adhesive bonding, you’ll want to understand its benefits, know the materials you can expect to bond and make sure the bonding house can answer the questions above satisfactorily.

Exclusive – 3 Tips to Eliminating Contamination in Aerospace Components

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At PTI, our passion is helping our clients reduce their manufacturing lead times.  Every month, our experts will share their insights and experience on the specialized processes that we deliver, on time, every day for our aerospace, medical, automotive and commercial customers.

This month, we will be focusing our attention upon contamination in aerospace components.  Today’s significant technological advances and the advent of nanotechnology, components that are exposed to any outside contamination, in some cases as small as 5 microns, could suffer catastrophic failure.

Overview

The importance of eliminating contamination in aerospace components first became relevant during the Second World War with the development of the Norden Bombsight and the first navigational gyroscopes.  What the military discovered was that even the smallest particles, less them 50 microns, would cause either of these devices to malfunction.

The technological advancements that followed the war came with a significant challenge: they required ever increasing degrees of cleanliness.  The development of cleanliness standards for critical components was the direct result of satisfying the need for common terminology and standardization.

In 1962 a military standard, known as MIL-STD-1246 was created to establish guidelines and requirements for the specification of cleanliness levels essential to product reliability and quality.  In 1997 the U.S. Army commissioned the Institute of Environmental Sciences and Technology (IEST) to adapt this military standard and create the industry standard knows as IEST-STD-CC1246.

Today, the importance of this standard extends far beyond military applications.  Many non-military manufacturers have discovered that obtaining optimum performance from their product is directly linked to its cleanliness.  The process of eliminating contamination to this standard is known as Precision Cleaning.

3 Tips

PTI Precision Cleaning expert Chuck Osborn offers these 3 Tips for Eliminating Contamination in Aerospace Components:

  1. During the initial phases of manufacturing, you should start off with a Cleanability study. Look at the part from the standpoint of “will we [or someone else] be able to clean out the foreign object debris (FOD) we are going to generate in making it”.
  2. To achieve highest levels of cleanliness on a finished component, it is critical that these components have in-process cleaning done to them throughout the entire manufacturing cycle.  Our research and studies have shown that not all manufacturing debris can be removed during a single Precision Cleaning process at the very end of the cycle.
  3. If you are using water based machining coolants during the manufacturing process, make sure that you flush it out of internal passageways and off of external surfaces immediately after each machining operation. Water based coolants have a tendency to gel and trap FOD in the part, making it extremely difficult to remove.

Learn More

If you have any questions about how our Precision Cleaning specialized processes can eliminate contamination in your critical aerospace components, or would like more information on any of our other specialized processes, please contact us using the form on the right.