Surface Preparation for Adhesive Bonding

/0 Comments/in , /by

adhesive-bonding-homeWhen making a quality adhesive bond, the first critical step is selecting the proper adhesive. Once the adhesive type is determined, the second important step is surface preparation.

Adhesive bonds are made to adhere other components to substrate surfaces, but because most surfaces are covered with contaminants, if not removed, bond failure will often result. Even microscopic surface contaminants can obstruct the surface, creating weak boundary layers which drastically reduce adhesion effectiveness.

A typical substrate surface exhibits contaminants in several layers:

  1. Dust, parent material and other loose particles make up the outermost layer.
  2. Oils and grease comprise the next layer.
  3. Oxide films, rust, molds, and additives such as paint and sealants are potential boundaries embedded into the substrate as the innermost layer.

With proper surface preparation, bond failure can be avoided. Pre-Bond treatments vary depending on the type of substrate material as well as the structural bond required.

Depending on the substrate material, surface preparation can include three steps:

  1. Degreasing: Degreasing with a solvent or aqueous detergent removes the outer layer of contaminants such as dust, metal chips, grease and machine coolant. To check for sufficient cleanliness, a water break test is performed, water is sprayed onto the part, if it runs off in a continuous sheet it’s clean, if it beads up like a freshly waxed car it means the surface isn’t clean enough.
  1. Abrading: Abrading eliminates the layer of films, oxides, rust, and paint clinging to the surface. All loose particles from abrading must be removed with degreasing and cleaning.
  1. Surface alteration: Certain materials present the greatest challenge in adhesive bonding, such as rubber, some plastics, and metals such as copper, stainless steel, and aluminum. Changing the surface property of these materials increases the surface energy for best adhesion. PTI uses media blast cabinets as the preferred method of abrasive blasting because it cleans surfaces better and faster than the traditional techniques of sanding and wire brushing.

All surface preparation methods must include a final cleaning and drying before adhesive bonding occurs, this is customarily done by hand wiping with a high purity solvent, the bonding must be done as soon as possible so surfaces do not become recontaminated.

For every material and surface there is a right combination of adhesive material and surface preparation.  We employ our many years of experience to Identifying the best combination that will be the best for your substrate application.

PTI’s special processes includes advanced precision cleaning technology and a dedicated 38,500 SF adhesive bonding facility that maintains two Contamination Controlled Areas for all your one-stop process needs.

Shut Down Assembly Line Demands Rapid Response

/0 Comments/in , , /by

Depositphotos_49175383_m-2015A nearby molding company recently experienced a product failure that forced their customer to shut down their assembly line. The OEM is a well known, top-selling pickup truck manufacturer and the molding company’s most profitable product line. The urgency was unmistakable.

It began as a panic-stricken call on our toll-free number. The man on the other end of the line explained the predicament. The company molds a small plastic box that is used as a switch that sits under a brake pedal. The switch activates the brake lights on a popular full size pickup truck.

Press the brake pedal and the switch turns the brake lights on. However, the system was no longer working. After switching from a straight plastic polymer to a fiber-filled polymer, the product failed. After assembly, some of the fibers were breaking off and getting stuck in between the electrical contacts and causing the switch to fail.

The entire operation came to a standstill, the whole truck pickup assembly line shut down, and workers were sent home. PTI needed to help them solve the problem, saving both the American-made pickup truck manufacturer and the molding company from an immense potential setback.

Due to the high volume and fast turn times on this particular part, the molding company cleaned the boxes themselves in their own plant. However, they didn’t have a way to test the part for cleanliness. Cleanliness testing is a crucial step in proving the cleaning process adjustments are effective and producing FOD-free parts.

The molding company had a courier ready, and as each new iteration came off their cleaning line, he immediately drove the samples to PTI for cleanliness testing. PTI’s technician was on standby, testing the samples as soon as they arrived. Once PTI had the test results, the technician phoned the molding company.

Based on PTI’s findings, they tweaked their process accordingly and then sent another sample for evaluation. This process took three adjustments and three trips back and forth by the courier, but in the course of a single day, they got the parameters exactly right.

In this cleanliness case study, the customer corrected their problem within a matter of hours. PTI’s rapid response was critical to solving this part failure. Contact PTI at 1-800-318-8438 for immediate solutions to your special process needs. PTI sets the industry standard for accuracy, reliability, and customer-driven response.

Critical Pressure Testing for Leaks

/0 Comments/in , /by

header_nonwelded_quality_pressure-testThere is no such thing as a good leak. Whether you’re talking about a leaky faucet or a critical aircraft component, leaks are at best pesky and at worst potentially deadly.

This is why pressure testing is imperative for many types of devices, such as fuel systems, ventilation systems, and numerous other devices in the aerospace, medical and laser fields. Pressure testing for leaks in these industries relies on stringent standards to produce defined results on in-process and finished assemblies.

All these components require testing technology that meets specific leak-testing challenges. Different components are subject to different stresses and applications, giving each product unique pressure testing practices.

To pressure test certain components, the test pressure must replicate the working pressure. When the pressure is very high, the testing is more difficult and the safety precautions become more complex.

In order to remain competitive, manufacturers need high-quality leak detection testing that delivers accurate, reliable, and repeatable results.

Getting successful results requires multidisciplinary expertise from test professionals. Running realistic pressure tests safely, as quickly as possible, and at the minimum cost are also instrumental for your success. The right skills and equipment for complex pressure testing programs greatly reduces the failure of accidentally damaging a component during testing.

For precise pressure testing of your components, special process providers with the required high levels of quality certifications in leak testing equipment and experience are the ones to turn to. Working with a provider who can develop test specifications to your prototypes and standards can also help you to avoid purchasing expensive pressure testing machines for in-house applications.

PTI’s laboratory performs two types of pressure tests:

  • Hydraulic or hydrostatic Pressure Tests use water or oil as the test medium up to 4000 psi.
  • Gaseous or pneumatic Pressure Tests use air or non-flammable gas up to 2000 psi.

PTI’s pressure test applications include aerospace engines, medical devices and laser components. Our pressure tests comply with AMS 2610, AMS 2615, and many OEM prime specifications.

 

Inside PTI’s Adhesive Bonding Department

/0 Comments/in , , /by

BOND Dept. Employee Photo 006

Manufacturers are increasingly choosing adhesive bonding as the preferred method for joining components due to its many advantages over traditional joining methods. Adhesive bonding is a critical process and if done improperly can lead to system failures. Proper bonding techniques start with understanding the process requirements, properly maintaining your bond facility and inventory, and having highly trained operators to carry out the requirements.

PTI Industries Adhesive Bonding Department’s team of experts’ goal is to maintain compliance to all bonding process requirements to ensure your critical adhesive bonding needs.

How the department is organized
PTI’s Adhesive Bonding Department is organized by the different types of adhesive bonding methods and spec requirements for controlled areas. There are two contamination controlled areas that are maintained for temperature, humidity, and positive pressure. One area is for RTV (Room Temperature Vulcanizing) bonding, and the second is for epoxy bonding used in applications such as liner (metal to metal) and Teflon bonding. There are also additional environmentally maintained areas for other methods and specifications, such as magnesium bonding.

Maintaining contamination control areas
Calibrated controls for temperature and humidity are checked twice a day to ensure an acceptable specification range is met. Humidifiers and dehumidifiers maintain the proper humidity levels for effective adhesive bonding.

Approval processing for the right adhesive method
Each adhesive bonding method is specification driven and controlled. Nearly all prime manufacturers require approvals for the type of bonding that is required in the form of an overall approval for processing. They also may require specific approvals in the form of a technical plan or process plan for the parts being processed or the method of processing.

Getting the right fixtures and tooling
PTI determines the appropriate bonding tooling and fixtures required for each specific job. Tooling is designed and created by our bond technical leader, quality department and engineering department. Most tooling or fixtures can be made onsite in our machine shop.

Adhesive storage and quality control
PTI stores adhesives in three ways:
1. Room temperature cabinets
2. Refrigerators
3. Freezer

All storage options are quality controlled. The refrigerators and freezer are monitored with state of the art thermocouple chart recorders. The freezer is set with an alarm indicating variation above or below the acceptable temperature range. When technicians aren’t on site, any deviation is sent to PTI’s security company, who then notifies PTI.

Typical adhesive shelf life can range from six months to one year. Shelf life is monitored with an inventory control system that includes product labels and an online tracking system. All out time of adhesives are tracked and recorded.

Your Certificate of Conformance
PTI provides a certificate of conformance for all jobs and for all special processes in our support services as part of our quality assurance program.

Who works in PTI’s Adhesive Bonding Department?
The Adhesive Bonding Department team includes a Bond Manager, Bond Technical Leader/Expert, two Team Leaders, Expeditor, Quality Engineer, and Bond Operators/Technicians.

All team members undergo on-the-job training on systems, procedures, and processing. Classroom training, special program training, part and job specific training are done by the quality department, bond technical leader, team leaders and high level operators.

For any questions on PTI’s adhesive bonding special processes, please contact Jessica Taylor.

How Can Four Equal One? – A Case Study in Streamlining Multiple Special Processes

/0 Comments/in , , , , /by

blog-pic-41pti-300x245In a previous post we spoke about streamlining your special processes to improve your bottom line. Now we’ll take a look at how one part would move through our multi-process shop. Four processes can equal one when a part has four sequential special processes done in one shop on one purchase order. To illustrate this, let’s look at a section of the value stream map for a Locking Nut that mates up to an LPT Shaft, which ultimately ends up in a jet engine.

This life limited part starts out as a 410 stainless steel bar. After machining and heat-treating, we receive the part in to perform Magnetic Particle Inspection (MPI) which is a form of Non-Destructive Testing. This special process is done to ensure there are no cracks or voids in the parent material that could result in an in-flight failure.

Having passed MPI, the part travels immediately into our Dry Film Lubricant (DFL) Department, where it has a thin layer of Molybdeum Disulfide (a type of DFL) applied to its threads. This ensures it will rotate smoothly when mated up to an LPT shaft at assembly.

Next, the part moves right into our Bonded Products Division where a special low-friction fabric washer that we laser cut to exacting tolerances is adhered to its bearing surface using our Adhesive Bonding technology.

This special fiber washer acts as a maintenance-free thrust bearing when it mates up to the adjoining surface on the LPT shaft.

The final stop for this part is in our Precision Cleaning Division. Here it will undergo a thorough cleaning and inspection to a microscopic level to ensure there are no particles on it that could damage the part itself or other sensitive components within the engine during use.

It is PTI’s unique Multi-Process capabilities that make it possible for Four to equal One. Streamlining your processes in our shop will result in reduced shipping, handling, paperwork, downtime and all related peripheral activities that will save you money in the long run.

Reduce, Reduce, Reduce! – Improving Your Bottom Line

/0 Comments/in /by

PTI_Reduce-300x200We’ve all been hearing it, “reduce your costs and reduce your lead times.” Most of the time, it’s easier said than done. We have found however that streamlining your special processes is a great way to improve your bottom line. Just as if you were to streamline your manufacturing processes in house. Let’s take a look at some potential cost drivers: Handling damage, shipping expenses, downtime between processes and paperwork/administrative expenses.

Handling damage is a very costly problem and occurs more common than any of us would like. If we minimize the handling of the parts then possible handling damage will be minimized too. Meaning, the fewer times a part changes hands the less exposure to handling damage it’s subjected to.

Shipping expenses can add up fast whether you use your own truck to move your parts or if you use a common carrier. Using your own truck for multiple stops means more fuel used, more time for your driver to deliver to multiple stops and less time for your driver to do other tasks. Shipping using a common carrier will add up in the form of invoices for each outbound and inbound shipment. Using one special process supplier versus multiple suppliers will save you shipping expenses in the form of both time and money.

Decreasing the downtime between special processes will without doubt reduce your lead time. Parts having to travel to multiple locations are not being worked on when they are in route. Using a supplier that has multiple processes may be the difference of your part traveling 50 feet to the next process which takes a matter of minutes versus 500 miles, which may take several days of non-value added time.

Using multiple special process suppliers creates the issue of redundant paperwork. There’s an added cost in having to generate several separate purchase orders to various suppliers. A One Stop Shop option means less paperwork for your purchasing agents to complete which allows them to do other tasks with the time they will save.

Streamlining your multiple processes with one vendor results in fewer shipping costs, less paperwork for your purchasing agents, less exposure to part handling damage and less down time between processes all which will help you to reduce your costs and lead times. Reduces costs and lead times will result in an improved bottom line for your business.

Want to learn more about PTI’s special processes? Click the links below for more information on each process that we offer:

Magnetic Particle Inspection

/0 Comments/in /by

When looking for a reliable, economical testing method for detecting flaws and discontinuities in your magnetic parts without damaging the part in any way, a preferred method is magnetic particle inspection (MPI).

MPI is a nondestructive test method that detects linear, surface, and near-surface flaws in material that can be magnetized, or ferromagnetic material, such as cobalt, iron, nickel, or certain alloys. During MPI, small magnetic, iron particles are attracted to any defects on or near the surface of your parts.

Applications for magnetic particle inspection include many different industries, including automotive, power generation, medical device, and aerospace industries. Testing is done on a variety of product forms and at almost any stage in the component’s production cycle, including castings, forgings, and weldments.

MPI advantages include:

  • Quick and simple application
  • Ability to detect defects through thin coatings
  • Highly sensitive to surface and slightly subsurface flaws that will appear on the test part
  • Easy automation and high-volume production testing
  • Less costly than other quality assurance testing methods

Limitations to MPI are:

  • Part material must be magnetic
  • Limited detection for subsurface indications
  • The direction of the magnetic field must be accurate
  • Complex test parts sometimes pose difficulty with magnetic properties
  • Demagnetization is often required

Your parts are tested for defects on our wet horizontal machines following these basic steps:

  1. Surface preparation: Your part is cleaned of grease, oil, moisture, and other contaminants. PTI uses TriChloroethylene Vapor Degreasing, also used with the FPI method.
  2. Determine magnetic properties: Calculations are done to know the amount of current required to magnetize your part. Both the adequate strength and correct direction of magnetic field must be used.
  3. Magnetize component: Your part is magnetized with a magnetizing pulse that is applied in short bursts of a half second to improve particle mobility. It is then bathed with a light oil containing small iron particles which will line up along any defect.
  4. Visual inspection: A UV black light is used to look for defects that will create a leakage field. The iron particles will cluster at any flux leakage point, forming a visible indication to an otherwise undetectable defect.
  5. Subsurface flaw detection: Unlike FPI, MPI can show defects below the surface such as voids in a casting. Indications will lose definition as flaw depth increases.
  6. Demagnetize component: Special equipment that operates in the opposite manner of magnetizing equipment is used to reverse the magnetic field. Remaining magnetic fields can adversely affect machining and welding, and interfere with electronic equipment. Test oil is then removed by vapor degreasing.

PTI gives you multiple solutions to your special processes in one stop. In addition to our Nondestructive Testing, we offer Precision Cleaning, Shot Peen, and Adhesive Bonding.

This is the fourth (and final) in a series providing detailed information on the special processes provided by PTI.
Part One: Dry Film Lubrication Gives Critical Long-Term Protection
Part Two: Get Quality Control for Your Parts with Nondestructive Testing
Part Three: Liquid Penetrant Inspection Is Economical and Versatile

Liquid Penetrant Inspection Is Economical and Versatile

/0 Comments/in , /by

FPI-1024x746_cropped-300x219Liquid Penetrant Inspection is a nondestructive testing method used to reveal surface discontinuities by bleeding out a colored or fluorescent dye from the flaw. This process is called capillary action, where a liquid is drawn into a clean, dry defect through low surface tension.

Liquid Penetrant Inspection (LPI), also known as Fluorescent Penetrant Inspection (FPI), is one of the two most common nondestructive testing methods, a process that tests for discontinuities without damaging parts in any way. The other method is Magnetic Particle Inspection (MPI), which is limited for use on magnetic parts.

If your parts are nonmagnetic, the only option is Liquid Penetrant Inspection. It relies on using either an ultraviolet light for a fluorescent liquid penetrant, or a white light for a visible dye penetrant.

The two penetrants are classified by their sensitivity levels. Visible penetrant is red in color and represents the lowest sensitivity. Fluorescent penetrants are yellow-green and contrast with the darkened environment, representing the highest sensitivity to defects.

Liquid Penetrant Inspection and Fluorescent Penetrant Inspection consist of 6 steps:

  1. Pre-cleaning the part to be free of all dirt, oil, grease, paint, rust, or any loose scale that could prevent the liquid from penetrating the defect or cause false indications. For most parts, PTI uses vapor degreasing with TriChloroethylene. Solvents such as MEK or Acetone are used to clean Titanium parts where Tri-Chlor may have adverse effects. Any defects present must be open to the surface, dry, and free of contamination.
  2. Application of penetrant to the part’s surface has a dwell or soak time that allows the penetrant to permeate into any cracks and voids. The dwell time can be from 5 to 30 minutes, depending on the material of the part and the size of the potential flaws. Smaller defects require a longer penetration time.
  3. Excess penetrant is removed from the part’s surface. This prevents the possibility of masking defects from the developer by leaving a background. Without proper removal, false indications may also occur. PTI generally uses water to wash the penetrant off.
  4. Application of developer follows drying time in a convection oven. A thin, light coating of developer is sprayed on the part and a dwell time is again observed. The developer draws the penetrant out, creating a visible indication or flaw in the developer known as a bleed-out.
  5. The part is inspected using visible light on a visible dye penetrant, typically with an intensity of 100 foot-candles or 1100 lux. Ultraviolet or black light is used for fluorescent penetrant examinations. The correct length of time is critical. The length of an indication can increase with time as the penetrant bleeds out, causing an acceptable indication to become an unacceptable defect.
  6. Post cleaning of parts with water to remove all developer, and thorough drying after evaluation.

Liquid penetrant advantages include:

  • High sensitivity to small surface discontinuities.
  • Indications can reveal relative size and shape of the flaw.
  • Parts with complex shapes can be routinely inspected.
  • Few limitations to part materials, i.e., metallic and nonmetallic, magnetic and nonmagnetic, conductive and nonconductive materials may be inspected.
  • Inexpensive and fast inspection of large volumes and large areas of parts.
  • Visual representations of flaws are made on the part surface.
  • Portable and convenient process.

Primary disadvantages of liquid dye penetrant are:

  • Flaws must be open to the surface for detection.
  • Part surface must be accessible for examination.
  • Part material with porous surfaces can’t be inspected with LPI.
  • The part surface must be clean of all contaminants that could mask defects, including removal of any metal from wire brushing, shot blasting, or grit blasting.
  • Surface finish must be smooth before inspection, which could require grinding.
  • Proper chemical handling and disposal is necessary.

PTI offers both Liquid Penetrant Testing and Fluorescent Penetrant Inspection as a valuable tool during new construction and in-service inspections.

This is the third in a series providing detailed information on the special processes provided by PTI.

Part One: Dry Film Lubrication Gives Critical Long-Term Protection
Part Two: Get Quality Control for Your Parts with Nondestructive Testing
Part Four: Magnetic Particle Inspection

Get Quality Control for Your Parts with Nondestructive Testing

/0 Comments/in , /by

FPI-Dwell-1024x637-cropped-300x239Nondestructive Testing (NDT) is an indispensable cost-saving technique for your quality control process. Modern nondestructive tests are used to control manufacturing processes, lower production costs, maintain consistent quality, and ensure product reliability.

NDT determines the integrity of your parts without causing harm or damage to the test part. Tests that use destructive methods can only be done on a limited number of samples, whereas with NDT inspection, your parts can be put into service without fear of part failure.

NDT is the process of inspecting, testing, or evaluating your components for discontinuities and differences in material characteristics. Physical properties can also be measured, such as impact resistance, ductility, yield, tensile strength, fracture toughness, and fatigue strength.

The detection of flaws may involve cracks or inclusions in the welding and castings, or any structural variations that can lead to decline in strength and possible service failure. If your parts undergo conditions such as repetitive forces, extended wear, extreme loads, and high speed operation, nondestructive testing to monitor serviceability is a critical requirement.

PTI performs two methods of NDT to check for cracks or indications:

  • Magnetic Particle Testing (MPT)
    This type of testing is used for materials that can be easily magnetized, such as iron, nickel, cobalt, and some of their alloys. Powerful magnetic fields are concentrated and applied to the material, detecting surface and slightly subsurface flaws.
  • Liquid Penetrant Testing (LPT), also called Fluorescent Penetrant Inspection (FPI)
    This method can be used for non-porous, non-magnetic materials for the detection of surface discontinuities. A visible dye is applied to the part surface and discontinuities are detected using ultraviolet or fluorescent light.

Applications for NDT include aerospace engines and airframes, orthopedic and analytical equipment for medical devices, automotive, power generation, laser components, and heat exchangers. NDT can be used during the manufacture and service of your parts, assessing quality and assuring safe operation.

As the demand for product reliability and safety grows, NDT and other special processes must meet more stringent requirements. PTI provides one-stop, special processes for all your manufacturing needs, including Precision Cleaning, Dry Film Lubrication, Adhesive Bonding, and more.

This is the second in a series providing detailed information on the special processes provided by PTI.

Part One: Dry Film Lubrication Gives Critical Long-Term Protection
Part Three: Liquid Penetrant Inspection Is Economical and Versatile
Part Four: Magnetic Particle Inspection

Dry Film Lubrication Gives Critical Long-Term Protection

/0 Comments/in , /by

dryfilm-homeDry Film Lubrication (DFL), also known as solid film lubrication, is the ideal solution for lubricating your parts when liquid-based lubricants fail to function properly. The dry film protective coating is more reliable for reducing surface friction between part surfaces.

For operations where cleanliness of your parts is critical, dry film coating offers a protective layer that won’t become easily contaminated by attracting dirt, metal, or other foreign particles. It provides long-term protection in conditions where damage occurs from lack of use, and interacting surfaces that are immobile seize up. Rust, corrosion, and oxidation are prevented in parts that could undergo damage before even being put into service.

Dry Film Lubrication advantages include:

  • Unaffected by extreme hot or cold temperatures
  • Excellent load-bearing capacity
  • Long-term protection, including storage
  • Effective moisture barrier
  • Clean, dry, and odorless
  • Appropriate for all metals, as well as plastic, wood, and synthetics
  • Resists contamination or removal by most solvents
  • Ideal for components that have to be removed repeatedly from inaccessible areas

PTI uses graphite and molybdenum disulfide (MoS2), or moly, as effective dry film lubricants to protect your parts’ surfaces when liquid lubricants won’t survive. The effect of these dry film coatings is similar to a person trying to walk across a floor covered with layers of playing cards. Each card slides easily against its contacting card, creating a reduction in total surface friction and resistance.

The DFL can be applied by dipping, brushing, or spraying. PTI typically uses spray, because both graphite and moly are suspended in a solvent that acts as a sprayable carrier similar to paint. The solvent evaporates off your part, leaving the dry film coating as a protective coating.

Dry film lubricants are used in many applications, including engines and airframes for both commercial and military aerospace, ground engines for power generation, and laser components and heat exchangers.

Many specifications for solid film lubricants require an additional process before it’s applied. Precision cleaning, vapor degreasing, passivation, and other special processes are performed to ensure maximum results in adhesion and effectiveness of the dry film coating.

At PTI, your special processes are available at one stop, saving you time and money with qualified solutions to your manufacturing needs.

This is the first in a series providing detailed information on the special processes provided by PTI.

Part Two: Get Quality Control for Your Parts with Nondestructive Testing
Part Three: Liquid Penetrant Inspection Is Economical and Versatile
Part Four: Magnetic Particle Inspection