Functional Testing Solutions For Brake Calipers

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The brakes are the most important safety feature of any vehicle, and the calipers are one of the most important components of the braking system. They apply the force necessary to slow and stop the vehicle. Producing quality calipers that stand the test of time, wear & tear and is essential to safe operation. If the calipers aren’t working, the car will just keep on going—even when one doesn’t want it to.

History

Disc brakes came on the commercial vehicle market in the 1950s. They represented an improvement over older drum brakes, which were prone to overheating and deteriorating performance over a short amount of time. Nearly all cars and trucks known have front-end disc brakes; some less expensive models still use drum brakes on the rear axle.

The standard brake caliper contains metal plates on both the outside and inside face of the rotor. The plates are faced with brake pads, which are the point of contact between the calipers and the rotors. When you depress the brake pedal, brake fluid flows through a master cylinder, which is linked to a piston housed within the calipers. The piston presses against the pads and forces them against the rotors. The action of friction slows down the rotor and the wheel.

Floating and Fixed

Floating calipers have their hydraulic pistons on the inboard side of the rotor; they move in and out as the brake pedal is depressed. Fixed calipers have their pistons set up on both sides of the rotor and apply pressure directly from both sides, allowing them smoother operation and more braking power; the floaters, however, are less tolerant of any defects or warping of the rotors.

Construction

Brake calipers can be one or two pieces and contain pistons or cylinders made of aluminum or steel. Two-piece designs are less expensive to manufacture, but have some disadvantages, which includes flex, less present in one-piece designs. Brake calipers hold the brake pads and have channels that accept the hydraulic brake fluid that activates the piston to push the brake pad against the rotor.

Materials

Most brake calipers consist of aluminum, as aluminum is very strong, but a light material that can handle the constant wear that exists in the braking system. Minimizing weight is crucial to the design of any vehicle and using forged or cast aluminum brake calipers helps accomplish this goal. Sometimes magnesium alloy is used, but it is expensive and often reserved for race cars. The brake rotors are made of a harder metal, as the friction against the rotor face during braking can bend or warp lighter metals.

The InterTech Solution for Testing Brake Calipers

Here’s one example of a turnkey system designed and built by InterTech Development Company in the USA. Do bear in mind that this technology is now available in India to best ensure that your products are tested with a robust and reliable system while ensuring that your parts meet the standard and quality requirements of your Customers.

brake-caliper-testing-system-test-stand

brake-caliper-testing-system-test-stand

 

Features

Components are leak tested to a 3 sccm. limit at 5 psig.

Piston retraction is gaged within a 0.010˝ window after venting down from 200 psig.

An InterTech M-1075 Mass Flow Leak Detector controls the leak test cycle.

Benefits

Reliability: System operates in a fail-safe mode with self-check features.

SPC Capabilities: Test results may be transmitted via RS232 interface or stored on disk.

Measurement Capabilities: Test R&R meets QS9000 requirements.

The Brake Caliper Functional Test Cell automatically tests and marks r.h. and l.h. calipers at a rate of 211 pph.

 

Follow the InterTech India blog for more solutions on leak and functional testing. For sales enquiries, you may contact us at;

Mobile: +91 994 032 0718

eMail: ajay@intertechdevelopment.com

Land phone: +91 44 4211 2525

Sales & Support: Chennai, India

 

 

 

Source: eHow.co.uk & eHow.com

InterTechdevelopment.com

 

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Leak Testing Fuel Injector Components

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A vehicle’s fuel injection system is responsible for injecting fuel into the engine cylinders, where the gas is burned to produce engine power. A leaky fuel injector, which is a common fuel injection system problem, can significantly compromise engine performance and produce a variety of symptoms.

As described in this article on eHow.com, small things like an erratic engine idle, a misfiring engine, reduced gas mileage and worst case, an excessive fuel leak onto the hot surfaces of the engine intake manifold or engine block causing the fuel to ignite and cause an engine fire. These problems can be arrested in the first instance with accredited testing systems.

Faulty fuel injector components not only are a threat to the end-user / consumer’s life, they also make terrible testimonials to your quality control. That we know isn’t the ideal situation for a component manufacturer, be it of any size.

InterTech’s leak testing solutions offer you unsurpassed excellence in testing solutions, both leak and functional. Here’s one such solution that has helped many manufacturers of fuel injector components to test and verify leaks in their manufactured components.

The Challenge

Fuel injection components often demand 100% leak testing to limits as low as .01 sccm with cycles as fast as 2.5 seconds, 10% R&R quality requirements, while also displaying significant part temperature variations.

Separate tests with different limits are typically needed in the same test cycle for body welds, seat leakage, and overall leakage. Integration of instrumentation software, fixturing and test circuit is essential, as is complete test documentation.

DR-109-Fuel-Injector-Components

Fuel Injector Test Fixture and Parts

Test Process and Solutions

InterTech’s downstream test process features a patented Micro-Flow mass-flow transducer to provide 10 times greater leak sensitivity than any other dry-air test method. A test part is enclosed within a test chamber and pressurized; leakage is measured as a flow increase into the test circuit outside the part, eliminating the need and time for pressure stabilization inside the part. The test circuit is precisely engineered for minimum volume, enabling the Micro-Flow sensor to almost instantaneously measure flows with a resolution of .0001 sccm.

Critical for fast small-leak testing, all fixtures and clamping devices are designed and built for absolute stability to prevent part movement during testing. Seal positioning mechanisms consistently address the test part squarely and firmly, stabilizing their closure forces quickly to shorten cycle times.

Seals are designed for high durability to run thousands of parts per day without replacement. With these unique features, Micro-Flow dry-air test systems deliver .01 sccm testing with less than 10% R&R.

Special Features

  • InterTech’s Patented Bias-Leak checking is especially important for fail-safe operation whenever testing to less than 1 sccm. It uses low-level airflow to confirm test-circuit integrity before each test cycle.
  • Temperature compensation sharpens test accuracy and repeatability by nullifying test part residual heat from welding, fabrication, washing or even operator handling. Custom algorithms based on the test part’s unique cooling characteristics supply appropriate corrective responses across the test cycle.
  • InterTech’s S-3085 networking/diagnostic software graphically visualizes for greater operator control the factors that can compromise a good baseline zero, trigger false rejects or otherwise disrupt accuracy and repeatability.

Follow the InterTech India blog for more solutions on leak and functional testing. For sales enquiries, you may contact us at;

Mobile: +91 994 032 0718

eMail: ajay@intertechdevelopment.com

Land phone: +91 44 4211 2525

 

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InterTech M1075 – for unsurpassed leak testing speed and accuracy

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An InterTech Design Report

Our diesel engine mass flow technology shortens test cycle time by finding leaks faster to enhance manufacturing efficiency and process – significantly. Download the full report in a PDF format at:DR129_R1

The Challenge

Develop a production line solution to detect and repair leaks prior to hot testing. Eliminate the possibility of leak-associated defects getting through the system. Deliver accurate results in seconds, while not wasting time and money on hot test repeats.

InterTech M1075 – for unsurpassed leak testing speed and accuracy - using Mass Flow, Pressure Decay & Differential Pressure Testing

InterTech M1075 – for unsurpassed leak testing speed and accuracy

The InterTech Solution

InterTech M1075 dry air tests both the water side and the oil side of an engine block at the same time, up to twice as fast as other available options.

The water side includes engine block passages, water pump, heater housing, thermostat housing, associated hoses and the coolant half of the lube-oil cooler, creating a cavity of about 12 liters. The oil side includes engine block passages plus, front and rear gear fly wall housings, crankshaft seals, oil pan, intake manifold and the oil half of the lube-oil cooler.

This creates a cavity of up to 180 liters depending on engine model. The InterTech testing system avoids problems of pressure fluctuation in the supply line by using isolated air reservoirs. Because it is independent of plant air supply, it provides a direct and stable measurement of leakage.

The InterTech system simultaneously pressurizes both cavities and the reservoirs: the oil cavity to 2.5 psi with a reject limit range of .2 lpm to1.4 lpm (user selectable); and the water cavity to 10 psi with a reject limit of 25 sccm.

Any leakage causes the leaking cavity to lose pressure and the InterTech mass flow transducer reads the flow rate.

 

For a customised quote for your leak testing problems, contact our Indian office in Chennai at 044 – 4211 2525 / +91 994 032 0718 / +91 98409 14544

You may also email our Sales Reps in India at ajay@intertechdevelopment.com / ram@intertechdevelopment.com

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Leak Testing 101 – Part 4

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In parts onetwo, and three of this “Leak Testing 101” series, we discussed three methods of dry-air leak testing—pressure decay, differential pressure decay, and mass-flow leak testing—including the pitfalls and hidden costs inherent in two-step pressure testing methods and the higher accuracy of single point measurement mass-flow leak testing techniques.

 Is mass-flow leak testing always the best leak testing method? Absolutely not. When accuracy and cycle time requirements are not that stringent, pressure decay testing or differential pressure decay testing can be a better application match because test instrumentation does not require as much specialization and related cost. At the other extreme, when very small leaks of less than 0.01 standard cubic centimeters per minute (sccm) must be detected, helium mass spectrometer leak testing methods may be required. It is the only reliable method when an application requires detecting leaks as small as 10–4 standard cubic centimeters per second (sccs) or less.

There are several different helium leak detection methods:

Sniffer—The test item is pressurized with helium and an operator moves a sniffer probe connected to the mass spectrometer to localize the leak. This method is slow, nonquantitative but has the advantage of localizing the leak.

Accumulation—The test item is placed in a chamber and charged with helium. Helium leaking from the part accumulates in the chamber and after a certain amount of time, a sniffer probe checks for the presence of helium, i.e., a leak. While apparently inexpensive, this method has a number of shortcomings: presence of tracer gas from prior tests, lack of adequate circulation in the chamber, and long test times due to background effects. As a result, it will be difficult to provide quantitative testing with this method.

Vacuum leak testing with helium—Figure 1 shows how helium mass spectrometer leak testing proceeds. The part is pressurized with helium and the chamber is evacuated down to less than 0.1 mbar absolute to eliminate background effects. The presence of helium leaking into the chamber is then detected by the mass spectrometer.

Helium Mass Spectrometry Method of Leak Testing

Figure 1: Test item is pressurized with helium within a test chamber. The chmber is evacuated, drawing helium out of the leaking test item. Mass spectromter then samples the vacuum chamber.

Equipment costs, maintenance costs, extra time required to evacuate helium from test fixturing in between test cycles, and ever rising helium costs makes this method the method of last resort. Typical applications include: heating, ventilating, and air conditioning (HVAC) components; pace makers; aluminum wheels; and airbag components.

For these type applications where leaks of 10–4 sccs or less must be detected for product integrity or safety, helium has its well-deserved place in the repertoire of best-match leak test techniques to consider.

In the next part of this Leak Testing 101 series we will discuss miscellaneous other testing techniques including: hydrogen ultrasonic, bubble testing, and air under water.

If you would like specific questions on best practices for leak testing (and other testing topics) answered in future articles, please send me your questions at jhoffmann@intertechdevelopment.com.

 

Note:  The above article has been reproduced from an article written by the author for Quality Digest

 

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Leak testing 101 – Part 1

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Not too long ago, when you wanted a product to be leak-proof, you simply put it under water, made sure it didn’t bubble, and thereby concluded there were no leaks. Such “bubble testing” takes time and depends on the operator’s ability, making it totally inappropriate for the modern production environment. Also, it doesn’t generate the quantitative measurements that are the lifeblood of quality assurance engineering.

Dry-air leak testing methods—some of which can detect leaks as small as 0.01 standard cubic centimeters per minute (sccm)—are the methods most commonly used today by a wide range of industries—from medical devices, to automotive, to appliances, and aerospace, among others. These dry air methods enable quality managers to define leaks quantitatively.

“No leaks allowed” standards are concepts of the past. There are a variety of dry air leak test methods and best-practice techniques for each type of method, which will enable compliance to ISO 9001 and comparable quality management standards to be achieved. Generally speaking, these dry air leak test methods include;

  • Pressure testing
  • Differential pressure-decay testing
  • Mass flow leak testing

In addition, tracer gas testing and especially helium mass spectrometer leak testing, are used in more demanding applications where leaks as small as 10-5 standard cubic centimeters per second (sccs) must be detected in a production environment. If one truly understands leak testing application requirements and best practice techniques for these various leak test methods, the selection of which type of testing to perform is a rather straightforward matter.

The first step in designing a leak testing solution is to correctly define what the leak limits are. Leak testing applications laboratories begin with an engineering analyses of a specific application to determine and quantify how much a product or component can leak. Often, correlation studies are performed to verify if it is possible to use dry-air test methods instead of hydraulic fluids. Sample parts are tested as part of an initial engineering analysis. These determine the production requirements and leak standards to be achieved so that quality engineering of test solutions can begin. The first step in this process is to select the leak testing method that is the best match to application requirements.

In this “Leak Testing 101” series we will discuss the various dry air leak testing methods and the issues and techniques that affect testing costs and gauge repeatability and reproducibility (GR&R).

First, let’s take a look at the pros and cons of pressure-decay testing.

The big plus of pressure-decay testing—or at least the thought behind it—is that the leak detectors for pressure-decay leak testing have the lowest upfront cost. It is probably for this reason that the method is still in use, although in many applications the real costs of pressure-decay testing are actually much higher than many realize.

In the pressure-decay method for leak testing (see figure 1), a part is pressurized, the test circuit is isolated, and the pressure drop associated with a leak is measured. A transducer reads the pressure change. Calculations then convert these time/pressure readings into a measure of leakage rate. The higher costs of pressure-decay testing stem from the difficulties inherent in the test methodology. Pressure-decay leak testing is relatively difficult because measurements are highly vulnerable to changes in testing conditions such as drafts or temperature and there are often difficulties in determining the volume of test parts and test circuits, which must be known in order to calculate results.

Pressure Decay Method of Dry Air Leak Testing

Pressure Decay Method

Also, pressure-decay leak testing requires two measurements of pressure with sufficient elapsed time between measurements. When speed of testing is an issue, this built-in delay makes the pressure-decay method less desirable. More important, the two measurements and the time lapse significantly increase the potential for measurement error. The amount of time you need to wait between measurements varies. Sometimes, long intervals between measurements can make for extreme accuracy, but these long wait times are typically not practical. The larger the part volume, the longer it takes to measure the pressure drop. Moreover, very large flows are also impractical with pressure decay, because when pressure drops very fast, it will probably not be measured accurately.

Thus, although pressure-decay leak testing instruments have a relatively low upfront cost, the extra time it takes to perform testing (if the results are reliable enough for the given application) is another expense that needs to be factored in to overall cost. It can still be the best leak test method for a specific application, but the trend lines are in the other direction. Most applications now require tighter GR&R even for very low leak rates, often with large volume parts, and with a desire to keep test cycle times to the bare minimum to cut overall testing costs.When you factor all these considerations in, it often leads one to use other leak test methods instead.

In the upcoming issues of this “Leak Testing 101” series I will discuss differential pressure-decay testing, mass-flow leak testing, temperature compensation issues, and many other topics. By the conclusion of Leak Testing 101, my goal is to bring all quality managers up to speed on the real factors that affect leak testing cycle times, costs, and reproducibility.

If you would like your specific questions on best practices for leak testing (and other testing topics) to be discussed in future articles, please leave your comments and suggestions in the Comments area below.

ABOUT THE AUTHOR

Jacques Hoffmann’s picture

Jacques Hoffmann

Jacques Hoffmann is founder and president of InterTech Development Co., a world leader in test-centric assembly specializing in automated leak and functional testing with mass flow, hydraulic, helium, or pressure decay technology (ISO-17025 accredited). InterTech Development Co.-engineered solutions are used by hundreds of quality management, product design teams, and manufacturers worldwide and the company’s worldwide support organization maintains offices in North America, Asia, and Europe.

Note:  The above article has been reproduced from an article written by the author for Quality Digest

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Bench Top Operated Sealed Package Leak Test System – utilizing vacuum leak testing technology

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Automotive Electronic Control Units Parts are tested to 0.6 sccm accept / reject limit at 0.5 bar vacuum at a rate of 102 parts per hour in a test time of 22 seconds.

Sealed Package Vacuum Leak Test System

Proven InterTech technology and fixture designs ensure production and quality efficiencies. The machine is designed ergonomically for ease of operator handling.

An InterTech model M-1075 Leak Detector controls testing cycle – test results are automated for collection and analysis on a customer database. The test chamber is constructed from aluminum with a hard coat anodize finish and incorporates an integral latch to set the initial seal compression when closed.  A barcode scanner is interfaced to the PC via a USB interface. IDC Standard design results in a low cost solution implemented to meet tight customer delivery requirements.

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Vacuum leak detection – InterTech Research and Development Capability

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Intake manifolds are tested for flow and leakage under adjustable vacuum levels.

InterTech Vacuum Leak & Flow Test Instrument and Test Stand
    • An InterTech M-1075 Mass Flow Leak Detector controls the test cycle. Vacuum level in the manifold is electronically regulated from 0.2 InHg to 20.0 InHg.
    • Flows over a range of 30 sccm to 50 lpm are selectable and measured to an accuracy of 2% of reading.
    • The vacuum transducer is connected to the test part. When this circuit is evacuated and isolated from the vacuum supply, any leak results in a vacuum rise relative to atmospheric pressure. The transducer output provides a measurement of the vacuum rise proportional to the leak rate.
    • All test functions are menu driven and InterTech S-3085 software provides real-time test cycle display, test statistics and data storage.
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Few parts are as critical to a product’s success as the new Volt cooling cell

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That’s why InterTech’s patented technology was specified for mass flow leak testing.

The Volt Cooling Cell

The cell consists of two lightweight aluminum plates joined by a proprietary nickel-brazing process. Specially designed grooves stamped into the plates form channels that allow coolant pumped through the battery pack to flow over the entire cell surface. This ensures an even temperature distribution across the pack, without hot or cold spots. Heat exchanger integrity ensures that heat developed while operating the Volt, or when it is charging, will be properly dissipated to prevent damage to the components.

The InterTech Approach

InterTech was selected to evaluate testing and cycle time requirements for high speed
production line testing. At issue was the need to compensate for part expansion as pressure increases and for temperature effects during the test – while meeting stringent R&R requirements.

The InterTech Solution

InterTech’s M-1075Y and its’ patented technology ensure low cost testing, short cycle time, and ongoing repeatability. For example, to ensure reliability of this innovative new heat exchanger, the manufacturer required exceptionally demanding mass flow leak test parameters. InterTech recommended and met the requirement of testing to 0.3 sccm at 172 kPa. In fact, patented InterTech mass flow transducers can provide direct measurement of leakage down to 0.01 sccm.

Mass Flow Leak Testing Results in a 6 Second Cycle Time

The InterTech M-1075Y ensures smooth and accurate testing with uniquely operator-friendly technology, like our exclusive built-in R&R mode, which validates the repeatability–reproducibility of the test cycle.

The 6.5″ touch screen control panel has simple and intuitive operator-friendly controls which enable clear, legible display of real-time, mass flow leak test results in bright, brilliant colors. It also displays the test cycle in real time for cycle time optimization.

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Is Your Manufacturing Operation in China Costing More Than It Should?

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Repeatedly Re-Engineering Systems?

In theory, using low-cost labor in China sounds like the best way to lower production costs.  In recent years however, more often than not, companies are finding that quality standards suffer with assembly and test systems that rely on low-cost labor.  To meet ISO standards (ISO 13485, ISO 16949, or ISO 9001) systems get re-engineered, sometimes repeatedly, and with a high price tag.

Is there a way to Avoid These Costs?

YES— you CAN incorporate low-cost labor into even the most challenging assembly & test operations if sufficient steps are taken to error-proof systems.  In most scenarios, this means using manual labor to load and unload parts for testing, but also relying on specialized test instrumentation that is not only fully automated but is set up with Gage R&R of ENTIRE test systems, not just instruments, in mind.

Avoid Generic Off-the-Shelf Test Instruments

Off-the-shelf instruments usually add costs for test-intensive applications-whether they are in China or elsewhere.  Longer test cycle times are common, slowing throughput.  Off-the-shelf fixtures too usually bring problems of unwelcomed seal creep.

InterTech’s Shanghai Tech Center Provides Local Support

Globally distributed manufacturers know they can meet the highest ISO quality standards — despite the challenges of ensuring quality in multiple production facilities– when they add InterTech Applications Engineers to their team. To meet the needs of a growing roster of elite manufacturers establishing operations in China, InterTech opened its Shanghai Tech Center operation in 2004.
InterTech’s turnkey test solutions in China continue to set new records for achieving the highest quality standards at the lowest costs.

 

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