A challenge the economy still faces is inventory levels. Over the last twelve months every distributor, wholesaler and manufacturer did their best to scale back inventory to match the reduction in demand. Now that demand is starting to pick up, industries are trying to increase their inventory levels to match it. Of course the scar of bloated inventory levels is still fresh so everyone is being cautious.

As a result of many discussions that Earnest had with customers, we initiated the Less is More solution. Distributors didn’t want to buy five boxes when they only needed ninety-five pieces. We heard customers’ disdain for high minimum quantities on orders, which only added unnecessary (and ultimately expensive) inventory to a distributor’s warehouse. We responded.

While there are signs of economic improvement, we still see the need to support our customers with the Less is More approach. The fact is that inventory is a double-edged sword; it’s great when you have what the customer needs and it’s a burden when it sits on a shelf collecting dust. Here at Earnest, we are doing everything we can to make sure our distributors have inventory amounts that are relevant to their needs.

The mark of a healthy business is learning from the past and not repeating mistakes. Continuous learning and a willingness to change is key for success. Earnest continues to rethink how we manage our business to be a better partner to you.

Think back, think forward and tell us what you need to be better in 2010 and beyond. Earnest will deliver a customized solution for an Intentionally Better experience.

Sincerely,

Kirk Zehnder
President
kpz@earnestmachine.com

I’ve been thinking the same way.

I’ve had the opportunity to talk with more customers this year than ever before, and I’ve learned more about both your businesses, and ours. You’ve taught me that the most important thing for Earnest
to do is to be a Partner, to be more than just price and delivery and to add more value to what we do. In fact the catalyst behind our offer to ship you the exact quantity you need (“less is more”) came from
a customer who said that was the value she needed to find in a true partner relationship. When she needs eleven pieces, we ship her eleven pieces. When the market improves and she needs eleven
thousand…we’re ready.

Your business drives what we do and we are eager to partner with you to deliver exactly what you need. If you just need price and delivery, we can do that. When you need more from a partner, when you need your logo on the boxes, an exact quantity in each one, and a guy dressed in a gorilla suit to deliver it, we’ll make it happen.

You’ve helped us build a business that we are proud to call Earnest. I firmly believe the last eighteen months are so have provided tough lessons that will ultimately make each of us stronger. Things will turn around and together, as partners, we can take what we’ve learned and we can grow together, succeed together and win together.

Kirk Zehnder
President
kpz@earnestmachine.com

Earnest Machine Products testing lab is fully equipped to test and verify all the critical feature of a hex nut to ensure proper performance. Shown below are some of the key features that our lab sees from manufacturers that do not maintain the high quality standards.

HIGH QUALITY PRODUCT

POOR QUALITY PRODUCT

Concentricity of threads to nut body: Centering the threads to the body of the nuts is essential for proper torque tension performance. Poor quality nuts have holes that are not tapped concentric to the hex body. Non-concentric tapped holes create added strain to the bolt during assembly.

Perpendicularity of threads to bearing face: Threads that are not tapped at a right angleto the bearing face will result in bending strain in the bolt which can result in premature failures.

Bearing Surface Smoothness: Rough bearing faces prevent proper clamp loads from being developed in the assembly.

Nut Form: Poorly formed hex corners cause wrench slippage and weaken the hoop strength of the nut.

Our E8 Plow Bolts are manufactured with the precise balance between strength and hardness that meets the SAE J429 specification. This is not the case with all Plow Bolts. Some manufacturers adjust properties to achieve different results.

Let’s take the A9 for example. When compared on a dimensional basis there is no difference between the E8 and A9 products. The threads, diameters and lengths are the same, and the same sized bolts will fit the same applications. However, they will perform and deliver differently.

The A9 bolt deviates from the SAE J429 standard most notably with regard to heat treatment. This deviation creates a hardness level that does not meet the recognized specification. While the intent is to create a harder bolt, the process causes the bolt to become more brittle and the ductility of the bolt is sacrificed. In any application where impact forces are encountered, ductility is more important than hardness in avoiding brittle fractures.

All Grade 9 bolts (A9, F9, L9) are non-standard designations. Subsequently the head markings used (nine radial lines) on the bolt indicate non-conformance to the SAE J429 standard. In some applications this may be a non-issue. For safety sake, Earnest strongly recommends the use of SAE J429 conforming parts in every application that may encounter high impact stresses. When it comes to A9 VS E8, less is definitely more.

As an owner of a fastener company and an inquisitive person, Kirk stopped to pick up the bolt.  He brought it into the Earnest Testing Lab to determine what happened to cause it to fail.

The interesting characteristics of this M22 x 1.5 x 120 wheel stud were that the head had fallen off, the serrations on the shoulder were worn all the way down to the shoulder diameter and the first 1/2” of thread below the shoulder had been worn and corroded down to the minor diameter of the thread, removing almost all trace of the thread that had been present, yet the front end of the stud and the wheel nut looked in good shape.

It appears that the last time that the truck that this wheel stud was installed onto was in for service no one gave the wheel stud a full inspection  If the mechanic just gave this wheel stud a visual examination they would not discovered any of the damage and wear that was going on behind the wheel.  All the mechanic would see on a visual examination are the exposed threads and top of the nut that showed no signs of excessive wear or rusting.

Just because an assembly looks good does not mean that it is good.  Critical fastener assemblies must be inspected at regular intervals to ensure reliability.

Failure Analysis

Earnest’s testing lab went to work to determine the cause of failure and developing recommendations to improve the wheel bolt assembly to prevent future failures.

Earnest’s test lab is capable of testing the physical, dimensional and chemical properties of all types of fasteners (whether we stock them or not).  Our lab has the industry standards for both inch and metric fasteners that permits us to verify if the fastener was made correctly and our personnel has the fastener experience to recommend where improvements in design can be incorporated to improve the safety and reliability.

Examination of the top of the wheel stud showed that the strength level was still visible.  The “10.9” marking on the head showed that this product was designed to meet a property class 10.9 strength level per the requirements of ISO 898-1.

Failure analysis starts with determining if the fastener was properly made to the standard that it was designed to meet.

Earnest test lab has the capability to perform the following tests:

Physical Properties

1. Tensile Test / Proof Load Test:  Determines the actual strength of the product. Tensile testing is performed on studs and bolts.  Proof load testing is performed on nuts. Earnest’s tensile machine can test up to 400,000 lbs making it one of the largest in the industry.
2. Rockwell Hardness:  The hardness of a material provides a correlation to the strength of the material and the uniformity of the heat treatment.  Our Rockwell hardness testers are capable of testing all of the Rockwell scales (C, B, A, N, etc) and all superficial hardness scales.
3. Micro Hardness:  Micro hardness testing determines if a product has been carburized or decarburize which can result in premature failures.
4. Plating / Coating Thickness:  Our X-Ray Fluorescence plating thickness testing is a non-destructive test that measures platings and coatings thickness and can identify the major chemical analysis of the plating material.
5. Salt Spray Cabinet:  Our salt spray cabinet meets the requirements of ASTM B117 salt spray testing and can measure the actual hours to rust for plated and coated fasteners

Dimensional Properties

1. Thread Gaging:  Earnest’s lab has a complete set of Go and No Go gages for not only inch coarse and fine threads (up to 5” in diameter), we also have a complete set of gages for metric coarse and fine threads.
2. Contour Tracer:  A contour tracer can measure and verify the critical features of any thread form.
3. Geometries:  Intricate geometries can be easily measured with Earnest’s Smart Scope. The Smart Scope is capable of measuring linear and radius dimensions to an accuracy of .0001” in three dimensions, along with the capability to measure angles in all three plains.
4. Dimensions:  Earnest’s labs micrometers and calipers are calibrated and certified to exacting industry standards for precise linear measurements.

Material Properties

1. Chemical Analysis: Determining the chemical analysis of a material establishes the grade of material used in the manufacture of the product.  Our mass spectrometer is capable of determining the makeup of steel, alloy and stainless materials.
2. Microscopic Examination:  Microscopic examinations determine if defects are present in the material from either the raw material used, the manufacturing process or from heat treatment.

Conclusions

Earnest’s testing of the failed wheel stud showed that it was manufactured to the hardness level specified for a property class 10.9 strength level stud.   The hardness range showed that the heat treatment was uniform across the cross section of the product.

Core Hardness

Rc 35.8 / 36.6

Since the outside of the head was broken off starting at the fillet radius through the center of the head, it could not be verified if damaged had occurred to the fillet radius because of insufficient clearance between the edge of the material being clamped and the fillet radius.

Microscopic examination of this failure zone indicated that stress corrosion was occurring at the fillet radius.  Areas of high stress concentration make high strength alloy steels prone to stress cracking at areas where corrosion is occurring.

The ratio of the head thickness (7mm) to the body diameter (22mm) also adds to the potential for high stresses to occur in this fillet radius area.  Since the shear strength of alloy steel is 60% of the tensile strength of the material, the shear area of the head needs to be 170% larger than the stress area of the threads.  In this case the shear area of the head is only 150% of the stress area of the threads.

Recommendations

Earnest’s testing of the failed wheel stud did show that it was manufactured to hardness requirements of a property class 10.9 strength level stud.

The type of head failure evident indicated that damage had occurred to the fillet radius that permitted excessive stress to develop under the head which resulted in the head breaking off.

In order to minimize the stresses from occurring under the head it is recommended that a larger fillet radius be incorporated into the stud.  This will require that the material the stud is being clamped down onto also has sufficient clearance at the edge of the hole to prevent damage from occurring to the fillet radius.  The wheel stud should also have a larger head thickness to minimum stresses at the fillet radius.

It is also recommended that a more corrosion resistant coating be used on the wheel stud.  From the condition of the stud it appears that it was coated with a standard phos and oil coating.  In order to prevent stress corrosion from occurring it is recommended that a more durable barrier coating is used (like a Dacromet or Magni coating) that will prevent corrosion from occurring.

Today you may need for us to fill your order for ten pieces.

We can do that.

These are times that call for creative solutions in order for partners in business to be successful. We are committed to being flexible with standard operations in order to meet your current needs. Here’s what we know: demand for product is down, pressure is up, choices are tough and everyone (necessarily) is paying attention to even the smallest expense.

Historically, periods of great opportunity and growth emerge from economic downturns – and though the market seems to be stabilizing, we know that recovery will take time.

Looking toward recovery while living in the present – we have eliminated our fixed quantity policy. If you need 17 pieces, we will ship 17 pieces. We look forward to the time when this is no longer necessary – bottom line: your needs have always been, and will always be, a priority in the way we do business.

We are eager to break policies, break boxes and break a sweat to keep your business running right and to keep your customers happy.

When the economy improves, and when you need tens of thousands of pieces once again, we’ll be here as your partner. You are important to us. Our core values are, and always will be, firmly fixed on raising the bar with the purpose to be better: better for our customers, better for our employees, and better for our community. Better – Intentionally.

Let’s make the choice to get through the tough times and to be successful together in to the future.

Kirk Zehnder
President
kpz@earnestmachine.com

The customer said that in some cases, the socket would not disengage from the thread of the stud when the assembly tool was reversed. This would cause the stud to back out of the hub. The customer’s review of the assembly procedure indicated the cause of the studs backing out was the
result of the studs not being made to the requirements of the drawings. These discrepancies were noted on the studs:
• The ends of the studs were concave and not flat or rounded as required by IFI-528.
• The studs that backed out did not meet the decarburization limits specified in ASTM F568 (as referenced in ISO 898-1).
• The “Total Thread Length” exceeded the maximumlengths as defined by IFI-528.
• The studs were not marked for strength level as specified by ASTM F568.

The customer said the studs’ excessive decarburization in combination with the concave end was causing the drive socket to lock onto the stud creating a disengagement torque that exceeded
the torque required to back the stud out of the hub.

Test Parameters

Three samples of studs that had backed out of hubs were submitted to Earnest Machine Products for testing. The samples were inspected for compliance to the customer’s drawing for dimensional conformance. The studs were also tested for compliance to ASTM F568 for Property Class 10.9 for Rockwell Hardness and Decarburization. Testing was also done on stock samples to learn the percentage of the lot that exhibited the nonconformances identified by the customer.

Test Results
The three samples that had backed out during assembly were inspected to the requirements of the customer’s drawing and IFI-528.

Dimensional Requirements are seen in Table 1. The dimensions that are underlined in Table 1 do not meet the requirements specified.

Table 1. Dimensional Requirements.

Dimenstions that are underlined do not meet the requirements specified.
*IFI 528 specifies the “total thread length” as the distance from the end of the stud to the top of the extrustion angle.
*IFI 528 specifies that the points are to be flat or rounded (oval). Inspection of the studs from the lot showed that they are all concave.

Hardness Requirements. Core hardness readings were taken by sectioning the damaged thread end of the stud at one diameter from the end. Hardness readings were taken on the Rockwell C scale at the mid-radius and the average of four readings were recorded.

Surface hardness readings were taken by initially lightly sanding the surface of the shoulder to remove any oxides or scale and measuring the hardness on the Rockwell 30N scale. These are seen in Table 2. Hardness testing showed that the core hardness meets the requirements specified in ASTM F568 (and ISO 898-1). The surface hardness also meets the requirements of ASTM F568
that the maximum hardness does not exceed R30N 59. The surface hardness does fall well below the minimum core hardness specified for a 10.9 strength level product.

Table 2. Hardness Requirements.

A sample was tested for “partial decarburization” per the requirements of ISO 898-1 (Hardness Method). The sample was sectioned in the undamaged end of the thread. Knoop Hardness readings were taken at the required three locations on the thread. Per the requirements of ISO 898-1, the reading measured at location 2 must not be less than 30 hardness points
of the reading taken at position 1 (see Table 3).

Table 3. “Partial Decarburization”

Location	Hardness
#1	353.3
#2	306.3
#3	319.1

Testing showed that stud does not meet the decarburization requirements of ISO 898-1. The difference in the hardness readings was 47 parts between points 1 and 2 on the thread. Figure 2 shows decarburization in the shoulder and decarburization in the threads after the thread rolling operation.

Fig. 2 – Decarburization in the shoulder and decarburization in threads after the thread rolling operation.

Evaluation of Stock

Testing was then conducted on stock samples of the stud to determine the percentage that show signs of decarburization.The samples were tested by measuring the surface hardness on the shoulder of the studs. The hardness was measured using the Rc scale.

This testing showed that approximately 15% of the stock had surface hardness readings that measured below Rc 30 (with the majority reading in the Rc 5 to 10 range).

Testing was then conducted to compare the tensile strength of product that exhibited decarburization to samples that did not show decarburization.

The samples were tested by pulling them in the tensile tester to failure. The maximum load required to cause failure was recorded and the tensile strength was calculated based on the stress area of the thread. The results were recorded in pounds and converted to metric units (see Table 4). Testing showed that all samples exceeded the minimum ultimate tensile strength for a Property Class 10.9 Stud of 1040 MPa.

Table 4. Evaluation of Stock.

Micro-hardness readings were taken on one sample that showed decarb and on one sample that did not show decarb based on the surface hardness testing. The depth of the decarb was determined by taking micro-hardness readings every 0.002″ from the surface of the shoulder into the core. The samples were tested using Knoop hardness and then converted to the corresponding Rb or Rc hardness (see Table 5).

Table 5. Microhardness Readings.

Testing showed that the sample that measured low on the surface hardness has partial decarburization to a depth of 0.012″. The sample that did not measure low for surface hardness did not show decarburization.

Conclusions

Review of the nonconforming characteristics identified by the customer did show that the studs do not meet the drawing requirements specified in drawing 6.C09201-12, as follows:
• The ends of the studs are concave.
• Approximately 15% of the studs do not meet the decarburization limits specified in ASTM F568
(as referenced in ISO 898-1).
• The “Total Thread Length” exceeds the maximum lengths as defined by IFI-528.
• The studs are not marked for strength level as specified by ASTM F568.

The customer has also indicated that the two contributing nonconformances that are resulting in the studs’ backing out are the following:
• The points not being flat (or rounded).
• The presence of a decarburized surface.

This combination results in the drive socket becoming locked onto the stud, and then the resulting disengagement torque exceeds the toque that is required to back the stud out of the hub.

Sincerely,

Kirk Zehnder
President
kpz@earnestmachine.com

Many in the fastener industry use the term “hex bolt” and “hex cap screw” interchangeably; technically there is a difference between the two. The industry standard that defines the dimensions for hex bolts and hex cap screws (ANSI/ASME B18.2.1) specifies a slightly wider tolerance for hex bolts as compared to hex cap screws on the following features:

• Body Diameter
• Head Thickness
• Width Across Flats (and Corners)
• Fillet Radius
• Overall Length
• Bearing Surface Flatness

The standard also permits several features to appear on hex bolts that are not permitted on hex cap screws:

• 1. Die seam on bearing face
• 2. Swell on body under head
• 3. Non-pointed (or chamfered) end

Both hex bolts and hex cap screws are made with the same basic thread length and body length requirements (basic thread length = 2 x dia + 1/4” for lengths up to 6” long).

The general rule of thumb for distinguishing a “hex bolt” from a “hex cap screw” is to look for a washer face under the head; if it does not have a washer face it is a hex bolt. Note that the features that are permitted to appear on a hex bolt are based on the assumption that a bolt is always assembled with a nut and that the nut
will be used to tighten the assembly down. A hex cap screw is designed so that it can be tightened by either the head or with a nut.

Some of our customers perceive that a hex bolt is a lower quality item than a hex cap screw. From a strength standpoint, there is no difference between the strength of a Grade 2, 5 or 8 hex bolt as compared to a hex cap screw. Both items have equivalent strength and load carrying capabilities. The tighter controls on the fillet radius and bearing face does make the hex cap screw a better choice if the applications are subjected to fatigue forces.

Also note that you can always provide a hex “cap screw” when a hex “bolt” is referenced on an order, but you cannot provide a hex bolt if a hex cap screw is ordered.
The same features discussed above also apply to “Heavy Hex Bolts” and “Heavy Hex Cap Screws”. The term “heavy” refers to the fact that these items have one size larger width across the flats than a “regular” hex head bolt or cap screw. For example, a 1/2” diameter “regular” hex head has a 3/4” width across the flats and a 1/2” “heavy” hex has a 7/8” width across the flats.