The Rajhans Corpation was approached by a customer who was looking to die-cast parts and then use the parts “as cast” with no additional machining, resulting in a piece that fit together tightly and would be leak free upon assembly. Thanks to our expertise in die-casting, our team determined that the parts, if designed according to intent, may have issues regarding casting tolerance and measurement in the future. Knowing that, our experts compiled a list of suggestions that you can find toward the end of this report.

Challenges

In order to create the part as specified, a number of things that would need to be considered in order to guarantee success. Among them, the fact that the part would need to be overmolded in order to hold electrical connections in place. To inject the overmolding, our experts determined that the high tolerance areas within the piece would need to be sealed off, and that it would need to be done in a way that not only allowed the pieces to fit together, but also be measured, with precision.

Analysis

In order to create the part as specified, our team identified a number of things that would need to be considered in order to guarantee success. Among them, the fact that the part would need to be overmolded in order to hold electrical connections in place. To inject the overmolding, our experts determined that the high tolerance areas within the piece would need to be sealed off, and that it would need to be done in a way that not only allowed the pieces to fit together, but also be measured, with precision.

Solutions

After analyzing the challenges and collaborating with the client, our team reached a number of conclusions regarding the machining, tooling and overall production of the part. Firstly, it became clear that the sealing surfaces, as well as the mating parts where the surfaces join, will have to be machined to the specified tolerance. Secondly, our experts suggested that the part also be redesigned to allow for draft in the interior walls so that the part may be released from the die, and then have the draft be machined in order to bring the walls into tolerance for overmold tooling. Finally, as expected, issues arose when measuring the parts due to set-up of the parts and datum. To solve the problem, our team measured with the CMM and verified the dimensions through 3D scanning.

The following report is an analysis of the hole position tolerance for a handlebar weldment. We have further studied our manufacturing and inspection practices, and have determined that 100% of our parts meet the drawing requirements. We understand that there is an issue fitting the handlebars to the mating “pod” assembly, so you will find our suggestion near the end of this report.

Challenges

The pods don’t have dimensions corresponding to 492.4 and 547.6 mm. As drawn, the four tapped holes are not controlled as a pattern. As such, the tolerance for their locations is unknown. The pod – handlebar assembly uses countersunk head screws, which serve an aligning function. This restricts any relative motion between the parts when as screws are tightened, and takes up some of the fit tolerance. An M4 screw has a max OD of 4 mm. The nominal hole size in the base is only 4.5 mm. This allows for .5mm of misalignment between the pod holes and handlebar base holes. As each screw is tightened, the allowance is becomes even smaller for the remaining holes. This clearance is not sufficient to ensure all of the parts assemble together.

Analysis

Tightening the hole position requirements on the handlebar will make manufacturing more difficult, and will add to cost. As it is, about 10% of the production parts would have to be reworked or scrapped in order to ensure each part will fit the test gauge. It would be more cost effective to ensure the parts fit by enlarging the hole size in the handlebar bases.

Solutions

We suggest that the customer determines the value of T2 by capability study of the pods or some other means. The client can then calculate the required size for the handlebar base holes, and give this number to the The Federal Group.

How To Meet The Print Without Breaking The Bank. A case study in optical measurement innovation using automotive flanges manufactured by Rajhans Corpration

Introduction – small businesses need accurate measurements too

You have a small manufacturing business. But, you still need accurate dimensions for your production part qualification process. You can’t afford a full-blown metrology department with a giant CMM. There is an innovative solution using machine vision to measure your parts. A high-resolution off-the-shelf scanner can be combined with a free optical measurement analysis program to get you the accuracy you need. You can now enjoy this new part measurement capability. It’s a new complement to our suite of measurement devices now available for you.

Pictured Right / Above: The high-resolution scanner we used for this case study.

Advantages of optical measurement software

Optical measurement is a fast, economical way to measure features on planar surfaces.
Here are some ways that you can benefit from optical measurement software:

• Measurement values can be displayed using custom number formats—as required by you or your customer.
• Theoretical features can easily be calculated and displayed (e.g., locations of theoretical sharp corners formed by two edges or the center of a hole.
• Critical fitment data can be easily calculated and displayed (e.g., the distance between centers of two holes—to fit over two studs on the mating part).
• Custom variables can be defined for plotting and analysis.
• Editable text columns for comments or manual data entry can be easily added.
• Data (raw or formatted) can be easily exported to a spreadsheet or other analytical software for additional analysis.

Applications – accuracy without the complex setup

The inspection process demands accurate measurements. Every measurement system has its strengths and weaknesses.
The strength of this measurement methodology is that it provides capabilities that aren’t easily achievable with other available tools. The distance between hole centers is often a critical fitment criteria. Getting accurate manual measurements is tedious.
By establishing points on the arc of the circle, you can calculate the center point. The benefit of this methodology is that you can easily determine center-to-center distance conformance to the fitment criteria after you calculate the center points of two or more holes.

Pictured Right / Above: Calibration stick in blue. This is a measurement of a product. In red is the calculated distance between the center points of two holes—a tough measurement to get manually.

Observations – methodology leads to repeatability

This measurement methodology gives you high resolution — less than +/- 0.001” linear and less than 0.5° angular. The scanner resolution is critical for measurement accuracy.
The system is limited to the evaluation of planar / flat surfaces that will fit on the scanner bed (roughly 8.5″ x 11″ for our current setup). When used skillfully, it can give you an accurate visual record of the part analysis (see below).
Measurement systems that are not fully autonomous are susceptible to user variation (i.e., the user must accurately place the software’s visual markers on part characteristics).
Our operators are trained to produce accurate and repeatable measurement results for you.