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Tolerance & Fits (Part 2)

Tolerance and Fits Part 2

A Vital Part of the Metric System

In our previous blog post, we covered the tolerance system. By using the ISO tolerance system, any combination is possible to get the needed fit. In order to limit the number of tools as well as the number of machine elements, ISO created the base hole/base shaft system.

In the base hole system, the hole is given a fixed tolerance. Since it is easier to modify the diameter of the shaft, the base hole system should be given preference. Most metric reamers produce a hole tolerance of H7. This results in less required tools.

In the base shaft system, the shaft is given a fixed tolerance in order to achieve the required fit.

Here are some standard combinations of fits:

Snug Fit H7/s6
This is used in high pressure bolted joints. The tolerance of the shaft is larger than the hole tolerance and exceeds the zero line.

Sliding Fit H7/h6
This type of fit is used to fit parts that can be assembled and disassembled freely. The shaft tolerance is slightly under the hole tolerance.

Drive Fit H7/m6
For this type of fit, exact positioning is needed, usually in a shear load. The shaft tolerance is much larger than the hole tolerance and the shaft has to be driven into position by force.

Loose Running Fit H7/d9
In this combination, the shaft tolerance is much smaller than the hole tolerance with ample clearance. Used for bearing in off road machinery, farm equipment, and where there are large temperature variations.

Have more questions about tolerance systems or the different combinations of fits? We have the answers! Contact us at ProvenProductivity@bossard.com to start the conversation.


November 27, 2015
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Tolerance & Fits (Part 1)

ISO Tolerance

A Vital Part of the Metric System

In a previous blog post, we wrote at length about the benefits of metric fasteners – and the use of the metric system, in general. The importance of tolerance systems was mentioned, but not expanded upon. The ISO tolerance system is, in essence, the key to global interchangeability.

The key to understanding the metric system as it relates to fasteners is the understanding of its tolerance system. The inch/pound system tolerance is done by minimums and maximums that are determined by design.

The ISO fits and tolerance system is based on a number/letter system that relates to the ISO tolerance chart. This chart is applied globally and allows the designed parts to be interchangeable.

The letters indicate the location of the tolerance and the numbers indicate the tolerance range. The bigger the number, the bigger the spread between the maximum and minimum tolerance. Capital letters show internal dimensions (holes, sockets key, etc.) while lower case letters refer to external dimensions (shaft diameters, pin diameters, width across the flats, etc.)

Each letter has its exact location related to a so-called zero line. The zero line refers to the nominal dimensions such as nominal diameter and nominal length.

In our next blog post, we’ll cover fits as it relates to tolerances, so be sure to check back next week! Until then, if you’re interested in engaging further about tolerance systems, please do not hesitate to reach out! Contact us at ProvenProductivity@bossard.com to get the conversation started.


November 20, 2015
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All About Washers

washers

The use of incorrect washers happens more than you might think – and it occurs all across the globe. What are the consequences of using the wrong washer? The strength of the join is reduced and the risk of loosening in a dynamic joint is increased.

So how do you know which washer to use?

Comparing and contrasting lock washers, split lock washers and ribbed lock washers can help create a better understanding of the advantages and disadvantages of both types.

Flat washers are up first. When used correctly, flat washers can help reduce surface pressure on softer materials, minimizing the loss of clamp load due to embedment. You’ll notice that the bearing area is often larger than a screw or a nut. In addition to producing more frictional resistance, flat washers also protect softer materials and reduce the risk of loosening due to embedment.

You’ll need to reference the fastener property class to determine the proper washer hardness. Choosing the wrong washer hardness can increase the risk of embedment.

Split lock washers are up next. There is a misconception that these are added to reduce the risk of rotational loosening, but the true objective with split lock washers is to reduce the loss of clamp load due to embedment. Correct use will reduce the risk of loosening due to dynamic forces.

But the strength of this type of washer is often overrated, leading to a much higher risk of loosening due to embedment. Split lock washers are only able to withstand clamp forces introduced by fasteners up to property class 5.8. It is also important to mention that their effectiveness is very low or even non-existent when used with heat treated fasteners of 8.8 (grade 5) and higher.

Ribbed lock washers stand apart. These washers feature ridges on at least one side designed to anchor themselves into the clamped parts, as well as into the bolt or nut’s bearing area. The friction in the bearing area prevents spontaneous rotational loosening of the screw or nut by increasing friction between bearing areas. This washer is also intended to reduce the risk of embedment.

For the reasons stated in the paragraph above, ribbed lock washers represent a viable and effective alternative to flat and split lock washers.

Not sold on the idea of ribbed lock washers for your application? We’re here to help! Contact us at ProvenProductivity@bossard.com to start the conversation.


November 06, 2015
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The Importance of Perfect Preload

Die Bedeutung der perfekten Vorspannung

Never underestimate the importance of preload. Failing to achieve the correct amount can have devastating and far-reaching consequences. Here, we’ll address two of the most common failures that can occur in the event of insufficient preload.

Mechanical overload failure – including embedment, crushing, yielding and fracturing – is nothing you ever want to deal with. But excessive preload can result in exactly that. Too much applied torque will lead to failure at assembly, and the consequences of that can have a domino effect. This will add to subsequent service loads and exceed the strength of the fastener/joint material.

Specific problem areas related to mechanical overload failure include differing thermal expansion rates, material, and creep especially when the joints contain plastic or gaskets.

Insufficient preload can lead to transverse slip of joint members, which in turn can cause loosening. Self-loosening, leaks, slippage, squeaks and rattles are all things you don’t want. Ensuring that the preload is sufficient will help avoid a lack of clamp force and the ensuing effects.

Obviously, the importance of preload cannot be ignored. Failing to implement the correct amount will certainly lead to issues and complications you’d rather not have to deal with.

Interested in learning more about the importance of preload and the potential consequences of failing to use a sufficient preload? Contact us at ProvenProductivity@bossard.com!


October 30, 2015
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Metric vs Fractional Fasteners

metric fasteners

Metric vs Fractional Fasteners

Can’t decide between metric fasteners and fractional fasteners? Allow us to settle the debate.

There are several benefits to using metric fasteners, chief among them being that metric dimensions are globally interchangeable, enabling you to procure parts from anywhere in the world.

For this reason, metric fasteners help facilitate international communication and trade, in addition to lowering in place costs. Products made in the United States are easier to service and maintain and also become an easier sell overseas, due in large part to the interchangeability of products.

The metric system is also simple and logical. The advantages are myriad. In addition to the aforementioned interchangeability, the metric system also benefits from increased accuracy, and has been applied by almost all nations across the globe.

Metric fasteners are subject to the ISO tolerance system. This system system is the key to achieving lower cost and interchangeability globally.

For more information about the benefits of metric fasteners, click here.

The Bossard website also features a tool for converting between metric and inch fasteners. This converter – which can be found here – offers best proposals as you work toward a compromise.

Not sold on metric fasteners over fractional fasteners? The conversation doesn’t have to end here. Contact us at ProvenProductivity@bossard.com! We’re happy to continue this discussion with you.


October 26, 2015
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Fasteners for High Temperatures

Fasteners for High Temperatures

Temperature is an important factor to consider when determining which fastener is best suited for your application. Failing to take temperature into account can have severe consequences for your application. Here, we’ll cover various temperature ranges and the ideal fasteners for each one, with a specific focus on higher temperatures.

Temperature Range from -50 Degrees Celsius to 300 Degrees C
According to the ISO standard, standard property classes can be used for this particular temperature range. Your standard off-the-shelf 12.9 can be used, but it is important to remember that the 12.9 is limited to a specific range between -10 Degrees C and 250 Degrees C.

Above 300 Degrees C (570 Degrees Fahrenheit)
Low carbon steel or low ally steel can be used up to a ceiling of about 350 Degrees C (660 Degrees F). For this temperature range, the carbon content should be less than 0.4 percent.

Above 350 Degrees C (660 Degrees F) to 600 Degrees C (1,112 Degrees F)
Low alloy steels with an alloy element such as chromium, molybdenum, and vanadium are best suited for this temperature range. In addition to offering greater resistance to relaxation, these materials also possess tensile and yield strength that typically do not exceed that of property class 8.8.

Towards the higher end of this temperature range, best practices suggest the use of steels with higher content levels of chromium, molybdenum and vanadium.

Similar to the previous temperature range, the carbon content should be less than 0.4 percent.

Above 540 Degrees C (1,000 Degrees F)
Austenic steels, which are not heat treated, are best suited for this application. Their strength is achieved through work hardening. But depending on the environment, austenic steels or super alloys may have to be used for this temperature range.

Figuring out what best works with each temperature can be tricky. But we’re here to help! Contact us at ProvenProductivity@bossard.com if you have any questions about finding fasteners for high temperatures. The answers to your questions await!


October 16, 2015
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Cost Savings with Bossard Engineering Services

Cost Savings with Bossard

Imagine you’re building a skyscraper. You have half of the building completed when you realize that there was a mistake in the original design, and now you’ll have to start construction all over again, including tearing down what you’ve already done up to this point.

But what if you could avoid that miscalculation from the beginning?

This is the benefit of working with the Bossard engineers. Bringing our experts in during the early stages of your new product design can lead to a more efficient process and also reduce your costs. How do we accomplish this? Check out the infographic below.

Cost Saving Bossard

If you’re going to develop a new product, be sure that you’re doing the right thing from the beginning. With extensive knowledge and expertise in fasteners, coating, materials, and joint assembly our engineers can streamline your development process from beginning to end.

So what are you waiting for? Contact Bossard at ProvenProductivity@bossard.com now. Take the first step towards the perfect new product with one quick e-mail. You won’t regret it.


October 09, 2015
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Bossard Honored at 51st Annual Industrial & Technology Barbecue

Bossard is honored at picnic

The 51st Annual Industrial & Technology Barbecue was held on Wednesday, September 9th at the University Plaza Waterfront Hotel in Stockton, CA. The Greater Stockton Chamber of Commerce was the host of this special event, where more than 300 local business owners and employees gathered to recognize new and expanding manufacturers and industries in the area.

Bossard North America – specifically our warehouse located in Tracy, CA – was named one of the honorees in the category of “New Companies.”

To be eligible for the award, businesses must be located in an industrial zoned area, be in operation before July 1, 2015 and meet two of the following requirements:

  1. 20 or more new jobs in San Joaquin County
  2. 20,000 square feet or more of new or expanded facility
  3. $1 million or more in capital investment

Described as an evening complete with fun, camaraderie and networking, this barbecue has become known as one of the most popular events in the area.

Bossard could not be prouder to see that the hard work of our warehouse team in Tracy is being recognized by the esteemed members of the surrounding community. We are thankful to the Stockton Chamber for selecting our business for such a prestigious honor!

To learn more about Bossard North America or for more information about our warehouse located in Tracy, CA, please contact us at ProvenProductivity@bossard.com.


October 02, 2015
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Bossard Speed Rivets

Speed Rivets

Bossard Speed Rivets

What you need: An effective and efficient rivet engineered for the purpose of rapid and blind-sided installation, ideal for use with different materials and thicknesses.

What we have to offer: Bossard Speed Rivets.

You have a need – and we have the product to fulfill it.

The Bossard Speed Rivet is everything you’d want it to be. Pre-loaded on a one-way mandrel, this particular rivet can then be introduced right into the nose of the riveting machine. This allows you to fasten up to a continuous rate of 70 rivets per minute.

As far as materials go, the Bossard Speed Rivet can be used to fasten metals, plastics, composites, fiberglass and electronic components. The sheer of variety of different materials this rivet can be used with is evidence of how useful this particular product can be.

Electronic applications, sheet metal applications, vehicle construction, electric components, household appliances and metal cabinets are among the applications ideal for use with the Bossard Speed Rivet. Few similar products can compete with that kind of versatility, at least in terms of applications.

If quality and security are a concern, you can rest easy. The Bossard Speed Rivet, as is standard procedure with our products, is built to stand up to even the most painstaking scrutiny. There is no risk of losing the residual mandrel due to vibrations.

Bossard Speed Rivets are also held in place in the riveting tool to avoid a setback from being dropped onto the floor or into the application. Like we said before, we’ve covered out bases.

Interested in learning more about the Bossard Speed Rivet? Contact us at ProvenProductivity@bossard.com. Remember, this blog post is the tip of the iceberg when it comes to our products. All it takes is one e-mail to see the rest of what we have to offer!

For more shopping options click here.


September 25, 2015
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Benefits of Fastening with Magnesium

Fastening with Magnesium

Benefits of Fastening with Magnesium

I understand you’ve settled on using aluminum with your fastening application. But all I have is one question before you move forward: Have you considered magnesium as an alternative?

If you haven’t, you might not be aware of the benefits you’re missing out on.

One of the biggest advantages of fastening with magnesium is the reduced weight, as magnesium is approximately 30 to 35 percent lighter than aluminum.

Magnesium also boasts the highest strength-to-weight ratio of all common structural metals. For example, consider the wall thickness of 1.5mm magnesium versus 3mm aluminum.

Closer tolerances are also possible with the use of magnesium. Thixomolding, the process of heating magnesium into the barrel of a press, comes to mind as one of the chief possibilities.

In terms of production die life, magnesium also lasts longer than aluminum. There are numerous performance benefits from using magnesium, including better rigidity.

There are a number of items in which fastening with magnesium can be used. All you have to do is look around the house, in some cases. Electronics, powers tools (drills, saws, nailers, etc.), lawn and garden equipment, sports and leisure equipment and automotive parts are among the list of items.

Bolts and nuts, machine screws and thread-cutting screws are just a few options at your disposal in terms of fastening with magnesium, so your choices will not be limited.

Not quite sold on the idea of fastening with magnesium? Not a problem. Contact Bossard at ProvenProductivity@bossard.com and we will put you in contact with someone who can answer all questions you might have. Once you’ve started using magnesium with your fastening applications, aluminum will feel like a distant memory.


September 18, 2015
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