Technical Cleanliness in Progressive Stamping · 2020. 9. 14. · CEP Technologies Technical...

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Technical Cleanliness in Progressive Stamping

CEP Technologies Technical Cleanliness in Progressive Stamping | 2

Table of Contents

What is Technical Cleanliness? An Overview . . . . . . . . . . . . . . . . . . . 4

Why Technical Cleanliness Matters . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Understanding Particle Sizes, Counts, and Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

How Parts Are Cleaned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Part Inspection and How it Infuences the Manufacturing Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

What Causes Part Contamination and Ways to Minimize It . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Working with a Precision Stamping Partner to Meet Technical Cleanliness Specs . . . . . . . . . . . . . . . . . . . . . . . . .16



Most of the parts precision stampers manufacture are individ-ual components that are part of an assembly. In order for the final assembly to look and function correctly, each part must be made to spec. It’s easy to imagine how the wrong bend angle or a notch in the wrong place impacts a final product, but what about how clean those individual components are? Clean parts are about more than just avoiding grease or dust. In manufacturing, the concern is with the tiny particles that gather on a part’s surface. Many are too small to see with the human eye, but they have an impact on how parts fit together, how they perform, and even their durability. Industries from automotive and aerospace to medical devices and electronics, use precision-stamped components in their products. The trend in all of these is for individual parts, assem-blies, and finished products to be smaller and more electronically complex. Because there is little extra space, dust, fibers, and metallic particles can lodge inside and impact part function, part fit, and end-user safety. The key is technical cleanliness: to man-ufacture parts that meet specs for sizes, types, and quantities of particles, then keep them that way during transport to your facility so they’re in optimal condition at the point of assembly. This document focuses on technical cleanliness concepts and pro-cedures in single component precision stamping. Whether you’re familiar with specifying cleanliness and particle sizes and counts for your vendors or you need an introduction to get up to speed, you’ll gain a clear understanding of how cleanliness is defined and how it’s achieved and maintained.



What is Technical Cleanliness? An OverviewWhen specifying stamped parts for manufacture, it’s important to understand what technical cleanli-ness is, and what it is not. In simplest terms, cleanli-ness refers to the number, type, and size of particles on a part, sometimes called part contamination by particles. Degrees of cleanliness and methods for cleaning and analyzing results are described by in-ternational standards, which are based on research and experimentation by scientists and industry experts. Following these standard methods helps your precision metal stamper ensure a consistent end product that’s ready for use and meets your needs.

It’s also important for single-component manufac-turers, including precision stampers, to document their cleaning procedures and particle counts to show the condition of finished parts. Handling and packaging after the point of cleaning is also crit-ical to maintaining cleanliness levels - once they’re clean, the best practice is to keep them clean.

Standards and key concepts to understand when working with technical cleanliness specifications include the following:

• There is no single, one-size-fits-all definition of “clean.” Technical cleanliness does not refer to a standard quantity or size of particles, nor does it set a standard threshold for what is clean or not.

• • The meaning of “clean” depends on what an individual part is used for and what risks par-ticles pose to its end use and functionality.

• • The goal of part cleaning is to make the part as clean as necessary for assembly/applica-tion. Note that this is not the same as making it as clean as possible.

• • Cleanliness applies to the appearance and functionality of parts.

• Particles that cause part contamination are often too small to see with the human eye. Part con-tamination is usually described numerically by counting particles and noting their sizes.

• • Contamination from settling/gravity results

from dust and other particles in the air or in fluids that fall or settle onto a part.

• • Contamination from migration/transfer re-fers to particles that are picked up by moving parts from one location to another.

• Methods for cleaning parts include forced/blown air, washing (with water, detergents, or solvents), ultrasonic cleaning, physical agitation, CO2 “snow” blasting, and others.

• • The size, shape, and raw material of the part being cleaned and of the particles being re-moved may influence the cleaning and analy-sis methods used.

• • Not all cleaning and analysis methods are covered in the VDA and ISO standards, and not all may be considered valid for documen-tation (i.e. some methods used for internal benchmarking may not be acceptable for proving that specs are met).

• Cleaning and inspection contribute to the total acquisition cost of stamped parts.

• • Cleanliness testing usually happens at the start of each shift, though if additional testing or inspection is required, it can add to pro-duction time.

• • During the earliest phases of production, your vendor may perform extra cleanings and inspections. This helps identify steps in the manufacturing process where the most part contamination occurs. With this informa-tion, they can identify the point on the pro-duction line where cleaning is most effective in meeting specs.

• • Ideally, parts are cleaned only once during manufacturing. After cleaning to spec, cleanli-ness levels must be maintained to avoid hav-ing to reclean them.

• • Careful handling and packaging can help maintain cleanliness.

• • While your stamper may be able to achieve most any level of cleanliness you request, the smaller the particle sizes in your specification, the more you can expect costs to increase to achieve them.

• • Always consider if you’re requesting a level of cleanliness “above and beyond” what is necessary for proper part function and if it is cost-effective to do so.



• Different levels of cleanliness are acceptable for different applications.

• • Your stamper should be familiar with gener-ally acceptable particle sizes and counts for your components. They may be able to dis-cuss the impact of cleanliness requirements on things like cost and production time.

• • There may be a difference between levels of cleanliness necessary for part function and those that exceed true functional needs.

• Single-component manufacturers aim to achieve the specified cleanliness at the point of assembly. In other words, they will ensure finished parts are clean and packaged in a condition that is ready to use in assembly.

• Cleaning and inspection methods for individu-al components are outlined in Verband der Au-tomobilindustrie (VDA) 19.1 and ISO standard 16232

Your company or the client you supply may develop internal cleanliness and inspection requirements for finished parts, which your suppliers/vendors must meet and document.



Why Technical Cleanliness MattersUnique to each component part and its end use, cleanliness specs and a vendor’s ability to meet them affect appearance, performance, and safety. What’s more, a lack of cleanli-ness has consequences for the part in ques-tion, the finished product, and its end users. Part contamination always carries risk. In terms of appearance and part/product life, for example, water spots can make a gauge cover look dirty and possibly less appealing to a buyer. Or, stray metal chips trapped in an assembly can damage or weaken some parts. From a manufacturing viewpoint, clean parts look better and perform better, and often have a longer lifecycle. They also reduce the amount of scrap and reworking, as well as the result-ing extra time and money. Cleanliness reduces some economic risk for the supplier and OEM. Most critically, however, are the ways particles in-terfere with proper performance of a component and the safety of the final product it goes into. This is especially relevant in the automotive, aerospace, medical device, and food and beverage industries. As products become more technically complex, tolerances tighten, emissions standards become more strict, and electronics shrink. As a result, parts become more sensitive to the presence of particles. Numerous risks stem from malfunctions, includ-ing end-user or worker injury or death, property damage, product recall, supplier and OEM reputa-tion, and even company viability. These examples show how technical cleanliness directly affects per-formance and safety:

• Large or excessive amounts of particles can cause blockage in bearings, valves, and nozzles

• • Some very large particles, sometimes called “killer” particles, can cause a part to malfunc-tion or stop working correctly

• The presence of particles affects a material’s sur-face energy, which in turn effects surface adhe-sion of paints and protective coatings (e.g. a ship hull rusts from saltwater exposure where paint

didn’t stick; coating delaminates from polypropyl-ene)

• Particles can inhibit proper fit in an assembly or interfere with the mechanical action of moving parts

• • This is especially the case when tolerances are tight, part geometry is complex, or part features are prone to trapping particles

• Inflammable particles or fibers in heat-generat-ing devices or PCBs pose fire hazards

• Dust and metallic particles can cause short-circu-iting on PCBs, which can cause malfunction (e.g. controls for sliding doors, airbags, switches)

In addition to meeting specifications, vendors need to maintain records about their cleaning proce-dures, particle analysis and testing results, and any adjustments to the process for each batch of parts. Documentation is important for several reasons:

• It allows manufacturers to take action quickly in the event of a recall or other problem.

• If you can trace a problem back to a cleanliness issue and the specific point of production causing it, it is easier to justify the cost and time for that level of cleanliness (of course, the opposite is also true).

• In modern supply chains, with so many opportu-nities for damage and part contamination, it’s vi-tal to be able to trace each part backward in time and know what happened to it when.

• • This is critical when human health and safe-ty risks and liability concerns are involved.



Understanding Particle Sizes, Counts, and Specifications

For context, these are some examples of relative sizes of particles in microns.

Specifications for part cleanliness require count-ing particles – that is, the number of particles of various sizes within a given amount of space or on an individual part. Because particles are not always round, sizes are generally given according to Feret diameter, and expressed in microns. Feret diameter is a way of measuring particles that are not perfectly round, by measuring the distance between two par-allel lines on either side of the particle, as if it were gripped with calipers.

In order to make particle counting and analysis more uniform across industries and applications, standards documents like ISO 16232 and VDA 19.1 classify particles by size (size classes) and quantity (cleanliness level or “contamination level”) with a coding system, shown below:

Size Class

Size x [µm]

B 5 ≤ x < 15

C 15 ≤ x < 25

D 25 ≤ x < 50

E 50 ≤ x < 100

F 100 ≤ x < 150

G 150 ≤ x < 200

H 200 ≤ x < 400

I 400 ≤ x < 600

J 600 ≤ x < 1000

K 1000 ≤ x < 1500

L 1500 ≤ x < 2000

M 2000 ≤ x < 3000

N 3000 ≤ x

Cleanliness Level

Particle Count (per 1000 cm2 or

pro 100 cm3)

00 0

0 1

1 2

2 4

3 8

4 16

5 32

6 64

7 130

8 250

9 500

10 1 x 103

11 2 x 103

Cleanliness Level

Particle Count (per 1000 cm2 or

pro 100 cm3)

12 4 x 103

13 8 x 103

14 16 x 103

15 32 x 103

16 64 x 103

17 130 x 103

18 250 x 103

19 500 x 103

20 1 x 106

21 2 x 106

22 4 x 106

23 8 x 106

24 16 x 106

Human Hair50 - 70 µm

Grain of Sand 90 µm

Dust or Pollen < 10 µm

Combustion Particles, Metals, etc

< 2.5 µm



Companies generally include a Component Cleanliness Code (CCC) on part prints that specify acceptable levels and limits for particle sizes, counts, and distribution. Examples include:

A (B 15/C-E 14/F-I 9/ J-K 2)

V (B 12/C 10/D-E 8/F 3/G 2/H-J 00)

N (B-E 17/F-G 14/H-I 4/J-K 2/L-N 00)

• The first letter, A, V, or N, refers to the frame of reference for the particle count. These are standardized: number of particles per Area of 1,000 cm2, per Volume of 100 cm3, or per individual part.

• The letters in parentheses refer to the various size classes, either individually or grouped as a range of sizes, for example:

• • class B

• • classes C-E refers to classes C, D, and E

• The numbers following the letters refer to a code designating quantity, for example:

• • B 15 means up to 32 x 10exp3 particles that are between 5 and 15 microns in Feret diameter

• • L-N 00 means zero particles ranging from 1,500 to 3,000 microns in Feret diameter (which spans class-es L, M, and N)

So, for example, a nozzle might specify a cleanliness level of zero particles that are the same size or larger than the nozzle’s opening to avoid blockage.


https://www.linkedin.com/pulse/understanding-component-cleanliness-code-ccc-vda-19-iso-jack-griffes/


How Parts Are CleanedThere is usually more than one way to clean a part, but the best method is the one that achieves your cleanliness specs while staying cost-effective and efficient. Repeatable, reliable methods that get your parts clean in the shortest time possible take some adjusting because there are many variables involved.

Remember the goal should always be to get parts as clean as necessary for the application, not as clean as possible, which is usually not the same thing. It’s not hard to get wrapped up in the pursuit of a perfectly particle-free component, but in reality, certain sizes or amounts of particles may not have an impact on a part’s functionality. For example, for EMI/RFI shields, particles as small as 250 microns are usually the biggest concern; however, as re-quirements change the smallest allowable size may be 100 microns, or even 50 microns, especially in 5G applications. You’ll want to identify that critical point in order to avoid spending extra time and money re-moving more particles than is necessary for the part to function as intended.

We’ll focus on these common and widely accepted cleaning methods in single-component progressive stamping:

• Downward air blast onto parts secured in trays

• Aqueous ultrasonic wash, rinse, and dry

• Vapor degreasing and drying

Air blast

• Parts are secured in trays on a conveyor beneath a series of air jets directed down on them, blow-ing particles away.

• This method removes some (not all) particles pri-or to washing, though in certain cases it may be sufficient for cleanliness requirements.

• When further cleaning by washing is required, air blasting means parts are generally cleaner at the outset, which makes ultrasonic cleaning more ef-fective and efficient.

• Air blasting may reduce time spent in washing tanks for parts with soft metal coatings, such as tin or nickel plating, which can be susceptible to damage during extended ultrasonic cleaning.

Aqueous ultrasonic wash, rinse and dry

• Parts are secured in trays or baskets and fully submerged in the wash tank for a predetermined period of time called “dwell time.”

• A typical configuration has one wash tank and two rinse tanks. Some systems are integrated into the production line for inline cleaning, oth-ers are standalone systems for small batches or cleaning individual parts.

• Tank capacity ranges from a few gallons to 50 or 60 or more. A surfactant or detergent is often added to the water.

• • The chemistry and dirt levels of the wash wa-ter must be monitored and maintained. If de-tergent levels are too high, parts may be coat-ed with residue. If the solution is not changed periodically, particles from previous washes can add to part contamination.

• Trays can be rotated or oscillated to facilitate cleaning, or they may stay still for the full clean-ing cycle.

• Cleaning happens by ultrasonic cavitation:

• • An electric generator creates pulses of ener-gy which are transmitted into the wash tank through transducers (usually one on the bottom and two or more on the sides of the tank). The frequency of the pulses is mea-sured in kHz. The industry standard is 40 kHz, but frequencies can be as high as 180 kHz de-pending on requirements.

• • The pulses cause crystals in the transducers to expand and contract, creating alternating high and low pressure, which in turn creates microscopic bubbles.

• • When the bubbles implode, their energy is



a sealed chamber.

• Inside the chamber are two tanks (or sumps) filled with degreasing solution. One tank boils the solution, creating vapors that rise and degrease the parts suspended above. The other tank is for rinsing.

• • Most cleaning solutions have low boiling points between 105 and 165 degrees Fahr-enheit. The solution is specially formulated to be azeotropic, meaning all of the ingredients boil at similar temperatures. This helps en-sure there is no change in the concentrations of ingredients in the solution due to a variety of boiling points causing some to vaporize be-fore others (a situation called fractionating).

• At the top of the chamber, a refrigerated panel traps the vapor and causes it to condense back into liquid. The liquid falls into the second tank, keeping it full of distilled solution. Any overflow from this second tank pours back into the first, so it can be used again. The nature of this distillation process means the same solution is cleaned and recycled repeatedly, while any particles remain at the bottom of the boil tank.

• Parts are then submerged in the second tank to be rinsed. It’s also possible to add ultrasonic cav-itation to the rinse solution with transducers (see description above).

• Parts are then dried with hot air.

released, dislodging and removing particles.

• After washing, parts are sent through two sepa-rate rinse chambers to remove additional parti-cles and residues from cleaning solution.

• Parts are dried with hot air (see section on drying below)

There are several variables that help determine the most effective and efficient washing procedure, such as:

• Dwell time

• Frequency used to create cavitations: lower fre-quencies (20-30 kHz) create fewer and larger bub-bles with more energy; higher frequencies (60-80 kHz) create more bubbles with less energy, which can be helpful for delicate materials.

• Energy density/wave amplitude: the farther parts are from transducers, the less energy density and, therefore, the less energy from the bubbles

• Plating: damage can occur to plating from ex-tended dwell time. What’s more, if plating breaks down, those particles make the wash water less clean.

• Part geometry: part features like corners, bends, or embossed areas/depressions can trap parti-cles. Part design contributes to cleanliness, for example, in sharp vs. rounded bends and cor-ners.

• Water and cleaning solution: the concentration of detergents, wetting agents, and rust inhibitors can affect cavitation

• Volume and temperature of wash liquid: warm water of 50 to 65 C/122 to 149F is often used

• Gases: the presence of gases in the wash solution can affect cavitation or the overall chemistry of the solution

• Fixturing (i.e. trays or racks) to hold parts and the geometry of the part itself affect dwell time, transducer placement (i.e. energy density), etc.

Vapor degreasing and drying

• This cleaning process is used to remove stamping oils, grease, solder flux, and waxes.

• Parts are secured in trays and suspended inside

Hot air drying process after aqueous wash/rinse and vapor degreasing

After washing and rinsing or vapor degreasing, most

Cold TrapCold Trap

PartPart

Rinse SumpRinse Sump

Cooling Cooling CoilsCoils

Boil SumpBoil Sump

HeatHeat

Overflow

Overflow



parts are dried with hot air, though for some appli-cations, a hot dry may not be required. Dryers may be handheld or in a cabinet.

Because drying is a process of evaporation, the part itself is the source of heat that evaporates the water, leaving it dry. Because warm water evaporates more quickly than cold water, keeping the part’s surface temperature high efficiently replaces heat lost during evaporation and keeps the process going.

The drying step of the cleaning process is often where things slow down. Adding drying stations is one way to keep the process moving. Another option is using warm or hot solution rinse to boost drying efficiency. This is because water is more conductive than air, and therefore raises the part temperature more quickly. As a result, evaporation happens faster, less heat is lost, and less heat must be replaced by hot air.


https://techblog.ctgclean.com/2013/06/drying-heat-considerations-in-hot-air-drying/

https://techblog.ctgclean.com/2013/06/drying-heat-considerations-in-hot-air-drying/


Part Inspection and How it Infuences the Manufacturing ProcessOnce parts have been washed it’s time to deter-mine if they are as clean as required by specs. Just because the part looks clean doesn’t mean it is free of particles, so there is a standard inspection process for checking to see how many and what types of particles remain after washing, rinsing, and drying. Standard methods of inspection include:

• test the part’s surface for oils and films using test inks

• filter the final rinse water and examine the filter for particles and fibers

Keep these points in mind during post-cleaning in-spection and as you review the results:

• It’s important to have a clear and specific idea of what you want to know from testing (e.g. particle quantity, size, and material)

• Consider what you will do based on the results so you can take the most efficient and cost-effective actions if required (e.g. rewash with a different ultrasonic frequency? adjust wash liquid chemis-try or dwell time? make changes to the manufac-turing processes?)

• Checking individual parts visually can give you a general sense of their cleanliness, but most par-ticles are too small to be seen reliably with the human eye alone; final qualification of parts usu-ally requires a microscope.

• Depending on your requirements, extended analysis of filters and particles with an electron microscope or liquid or ion chromatography are possible.

• • These methods add time and expense be-cause they’re usually performed at external labs, so consider exactly what you need to know from analysis (and what you don’t).

• • Just because it’s possible to gather the infor-mation does not make it necessary or even

desirable if it won’t affect the manufacturing process or part performance.

• Other methods of inspection exist, such as inline rinse water analysis, digital image processing, and surface energy test inks; however, they may not be commonly accepted for final part qualifi-cation in all industries.

Optical inspection

This indirect inspection method, in which part rinse water is analyzed, is an industry standard. Because of the small size of most particles in question, con-tamination levels can be affected just by picking them up for examination. This can lead to inaccu-rate results, unnecessary changes to the manufac-turing process, and extra costs.

• Final rinse water is forced through a filter, the filter is dried and then examined under a micro-scope. Particle counts are charted by size and sometimes by shape (e.g. fibers, burrs/chips), then results are compared to the part’s speci-fications.

• In the earliest stages of production, washing and testing batches after each stage of manufactur-ing adds some time but can reduce costs in the long run. Testing can help identify:

• • Which stages/operations produce the most part contamination

• • Exactly where in the manufacturing process particle levels pass or approach acceptable limits

• • The single point in production at which parts need to be washed (i.e. parts should only be washed once during manufacturing - when they are at their most “dirty;” after washing, extra care must be taken to keep them clean, so they don’t have to be cleaned again)

• • Locations in the stamping facility that con-

Metallic Particle 162 µm X 22 µm

Nonmetallic Particle 156 µm X 20 µm



tribute to part contamination

Inks for surface energy testing

When parts will be painted, glued, or coated with a liquid an aspect of cleanliness called surface energy is a critical. When surface energy of a part is high, it can form a strong attraction to a liquid (i.e. paint, adhesive, etc.) and bonds well. Low surface energy forms a poor bond and may repel the liquid or allow it to delaminate or chip/flake off over time.

A simple and cost-effective way to measure a part’s surface energy is with liquid test inks. The inks come in a range of surface energy values, measured in milinewtons/meter. To avoid contamination of the part or the ink in the bottle, it is applied with a special cotton swab.

How the ink behaves when applied to the part de-termines how much surface energy it has.

• If the ink remains as a continuous film or band of color for three seconds or longer, surface energy is at least as high as that of the liquid – this indi-cates it will bond well with a coating.

• If the ink separates into droplets or beads in one second or less, surface energy is lower than that of the liquid – this indicates it may not form an optimal bond with a coating.

• By repeating the test with inks of varying surface energy values, it’s possible to pinpoint the part’s exact surface energy



What Causes Part Contamination and Ways to Minimize ItTechnical cleanliness procedures have two goals: minimizing particle accumulation during the manu-facturing process, and then maintaining cleanliness levels once they’re cleaned. As result, customers end up with a better product and increase the chances of saving money on cleaning time.

Many things contribute to part cleanliness (or the lack of it), and unfortunately, it’s not possible to control every possible source of particles. Testing and analysis, as described in section 4, along with environmental monitoring by airborne particle traps or visually inspecting work and storage areas can help establish a baseline of typical particle levels in a stamping facility. They can also help identify the biggest contributors to part contamination.

In general, there are two primary ways parts become “contaminated” with particles or fibers:

1. Settling/gravity (i.e. particles in the environment fall or collect on a part)

2. Transfer/migration/displacement (i.e. particles from another object end up on a part)

Each of the factors below can be causes of particles and fibers on parts:

Facility environment

• Airborne particles often come from dust or ac-cumulated dirt on blowers, fans, air returns, and filters.

• • Even breezes from windows, doors, and pass-ing equipment or people can pull in, disturb, or move particles around the facility.

• • Because the airflow in most facilities con-stantly shifts, it can be difficult to pinpoint where most contamination comes from.

• Walls, ceilings, and floors are common areas par-ticles gather. Dust and particles can cling to sur-faces, even vertical ones.

• • Particles can be transferred by air moving

over a surface or by a worker touching a table and then a part

• The layout of stamping equipment, machine cells, and workstations, as well as overall facility layout can affect what parts are exposed to and how dust and stray particles travel around.

• • E.g. proximity to internal and external doors and the outdoors, breezy hallways, and the path finished parts follow between worksta-tions or out for shipping

• After parts are cleaned, it can be helpful to isolate them to an intentional “cleanliness zone” to keep them clean

• • Such an area may feature smooth walls, con-trolled airflow, and protected entrances/exits that reduce the number of particles in the en-vironment and keep washed parts clean.

• • Among workers, a cleanliness zone fosters a mindset of extra care to keep parts clean and ensure proper handling.

• • It’s not practical to extend a cleanliness zone to the whole building, but ideally the mindset of preventing part contamination prevails fa-cility-wide.

• Finished parts, equipment such as tooling and dies, or raw material can pick up additional parti-cles and fibers from dusty or dirty storage areas so it’s critical to keep shelves and floors in storage areas swept out

• When boxes or bins are reused it can be helpful to ensure they’re free of dust and debris

• Stray fibers from cardboard box assembly may also be a source of part contamination

Manufacturing and cleaning processes

• Byproducts of the manufacturing process some-times remain attached to a part or transfer from one to another (e.g. metal chips, burrs, fibers, stamping oils)

• Cleaning adds to part contamination if detergent levels are incorrect or if water is not changed on schedule to remove accumulated particles

Operators/staff and other workers

• Training operators raises their awareness of the



environment greatly improves overall cleanli-ness.

• • Workers must realize the ways they can un-wittingly transfer fibers, oils, and particles from their clothing.

• • Their movements can also cause stray breez-es across a surface, kicking up dust or send-ing particles flying.

• Following correct part handling procedures prior to washing/rinsing of parts minimizes the amount and type of particles that accumulate on them – this means fewer particles to remove and a more effective cleaning process later

• Non-manufacturing staff and visitors to the fa-cility (such as customers, office personnel, main-tenance staff, or equipment/repair vendors) can track in particles or disturb dusty areas.

• • This is especially true if they’re working in ar-eas not frequently accessed such as behind equipment or under workstations

• Protective clothing including gloves, shoe covers, or gowns can reduce particle transfer. It’s import-ant that correct donning/doffing procedures are followed so the protective clothing itself doesn’t gather dust, particles, or fibers.

• Restrictions on the kinds of outside items al-lowed into the manufacturing, storage, and cleanliness zone areas are helpful in reducing stray particles and fibers (e.g. food, hats or simi-lar clothing accessories, boxes, paperwork, etc.)

Transportation and packaging

• Packing and unpacking raw materials and parts can disturb particles settled in box corners, on shelves, and on tables or floors

• Fibers from assembling or opening packs of card-board boxes often become airborne and can travel through the facility and settle on surfaces or parts

• Careful packaging selection and design contrib-utes to keeping clean parts clean. By isolating them from environment, preventing particles from being created due to abrasion, and avoiding corrosion (e.g. rust) due to moisture.

• Common packaging options include: tape and reel (to encapsulate the finished parts), trays to separate parts inside boxes (to protect plating and other delicate surfaces), vacuum sealing (to isolate parts and create a moisture barrier), and adding desiccants (i.e. silica packs) or nitrogen gas (i.e. to create a protective “bubble” around sealed parts).

• • Be aware that some packaging choices, such as cardboard and desiccant, packs can con-tribute to part contamination due to stray fi-bers.

• Pathways between workstations, from the pro-duction line to storage, or from the stamper’s facility into a truck for delivery/shipping expose parts to airborne particles and fibers.

• • It can be helpful to use protecting coverings and packaging as well as to clearly identify cleanliness zones to minimize further part contamination.

EnvironmentPersonnel

LogisticsEquipment

• Airborne particles• Transfered by air

moving or worker activity

• Isolation is important after parts are cleaned

• Packaging• Storage• Material Handling• Careful package and

storage selection is necessary

• Non-staff and visitor to the facility track in particles

• Protective clothing reduces transfer

• Training is essential

• Byproducts from the manufacturing process

• Incorrect detergent levels or water is not schanged on schedule



Working with a Precision Stamping Partner to Meet Technical Cleanliness SpecsIf you have a good working relationship with your manufacturing vendors, the quality of the products usually improves. And as an end user or supplier, obtaining high quality parts means you can provide a quality product to your customers – quality builds on quality.

When it comes to technical cleanliness of compo-nents, there are many things to consider beyond particle sizes and counts. Production costs and part performance are critical to your bottom line and to end-user safety. That’s why it’s in your best interest to find a precision stamper who can create the part you need, clean it to appropriate specs, and keep it clean on its way to you.

When sourcing product to a precision stamping vendor, forming a partnership matters. Here are some things to look for:

• Familiarity with common specification ranges for the parts you need and their function

• Ability to provide examples of previous test re-ports and analysis

• Understanding of the risks associated with infe-rior cleanliness

• Ability to discuss particle threshold values and indicate how critical (or not) it is to strive for very strict specs (e.g. is a higher particle count accept-able for safety/functionality requirements, espe-cially if it can reduce manufacturing costs?)

• Commitment to open communication and will-ingness to discuss all aspects of the manufac-turing process, part geometry, design consid-erations and intent, and how these relate to cleaning and part performance

• Ability to explain what goes into the costs of cleaning (e.g. manual testing process, employees

trained in procedures, time to filter water, then dry and analyze filters)

In a manufacturing environment where embedded electronics are the norm and precision stamped parts are shrinking, the complexities of technical cleanliness, and the precautions taken to maintain it, are critical. Cleanliness affects appearance but is even more important in ensuring finished products work correctly. Stray metal or fiber fragments and residual stamping oils affect assembly and perfor-mance in medical devices, automotive and aero-space vehicles, and countless consumer products.

The challenge for OEMs and precision stampers is achieving the level of cleanliness that meets specs for proper operation without spending excessive time and money on manufacturing. There are many ways to plan for and preserve cleanliness through-out the stamping process. An experienced custom stamper can work with you to optimize part design, manufacturability, and packaging that meet your requirements.


www.ceptech.net 914.968.4100

763 Saw Mill River Rd. Yonkers, NY 10710

http://www.ceptech.net

Technical Cleanliness in Progressive Stamping · 2020. 9. 14. · CEP Technologies Technical...

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