Friday, March 18, 2016

Wenzel's Granite Processing Plant

In 1885 in the German village of Gross Bieberau, a stone cutter began a business making tools, utensils, and decorative pieces from the stone of local quarries. He likely never imagined that 130 years later his family would still be cutting stone on the same spot, though for drastically different purposes. Today, Wenzel Steintechnik stands on the same ground, run by the same family as it has since 1885, making the granite bases and components for Wenzel CMMs.

A division of Wenzel Gmbh since 2006, Steintechnik evolved over the years from simple hand carved items, to designing and fabricating tombstones, evolving to the production of granite for industrial applications, and along the way became a critical partner for Wenzel.

Peter Heina, General Manager of Wenzel Steintechnik, if the Great-Great Grandson of the original stone carver, and has kept the family business moving forward and growing with the times. Currently, Wenzel Steintechnik is responsible for bringing the raw material in from the quarry, and processing it to rough size for our factory.

Work begins typically with a 35 ton block of raw material which is sawn into workable sizes for either machine tables, or components such as X beams. These smaller blocks are then moved to other machines for finishing to their final sizes. This may seem like no big deal, but having seen it in person, I have a new appreciation for the task. Working with such massive pieces, while also trying to maintain high precision and quality, is a balance of brute force and a delicate touch that requires a level of skill and passion to master.

This skill and passion extends outside of the Steintechnik facility though. Each year Peter makes
regular visits to the South African quarry where our granite is sourced, not only to maintain a good relationship with our vendor, but also to collaborate on selecting the individual blocks which will become Wenzel CMMs. In 2003,

Peter led a project at the quarry to improve their processes for handling the massive stones, in order to improve the quality and yield of the finished product which we receive at Wenzel Steintechnik. This allows us to make more, and larger pieces from a single block of stone, improving our lead time and effeiciency.

This spirit of continuous improvement carries on at our Steinechnik facility as well. Recently Wenzel has invested in a new 5 Axis vertical mill, to streamline the manufacturing process, and reduce the handling of the stone. This massive gantry mill allows Peter and his team to combine cutting, grinding, and milling operations into one, while also improving the cycle time of the processes themselves, which led to a 60% reduction in overall processing time.

With a working volume that can handle up to 6 large machine bases, Wenzel Steintechnik now has the capability for lights out production of granite, 24/7. Improvements like these allow us to reduce our delivery times to the end customer, and also increase the flexibility of our production schedule to react faster to changing demands.

Another more subtle change in the manufacturing process, happened some years ago, when the Steintechnik team began serializing all the components they manufacture. This allows them complete traceability form the time a block of raw granite leaves the quarry, until the pieces are assembled into a CMM.

Should problems arise with a certain component, all other components which could be affected can be easily contained and verified for their quality, ensuring that no quality defects escape the facility.

This may be something we take for granted in high volume production like Automotive and Aerospace, but it is unprecedented in the world of granite manufacturing.

But there’s more to the quality of our granite than just the size and shape. What about the mechanical properties? How do we ensure that the physical quality and the composition is what we expect? The technicians at the factory perform a variety of tests; they check the composition, perform physical tests, even grind and lap samples to ensure that the necessary flatness and durability can be achieved.

But when the giant monoliths are first received in Steintechnik, Peter Heina performs his own test, with water. Cutting a small sample from the block, Peter runs water over the stone, feeling it with his fingers. The way the block slides in his hands, how it absorbs or repels the water, whether bubbles form on the surface.

These are all indicators of how the block will perform during grinding and lapping, whether micro-fissures exist that will cause cracking and deformation. In essence, is it good enough for a Wenzel?

So why, you may ask, does this all matter? Why should you care about our granite? The fact is if we’ve done our job right, you never need to. The level of care we take to ensure that only the best material is used in the construction of our machines is a core principle, the center of all we do.

We build our machines on a 130 year old tradition of quality and care that ensures the highest level of precision, and durability. We take the time to use the best materials, and the best processes, building an accurate and stable machine so that you don’t have to think about it. Anything less, wouldn’t be a Wenzel.

Monday, March 14, 2016

Is the future now for your part?

The promise of the future has always been alluring, flying cars and the like. In metrology, which is a rather mundane endeavor, the promise of the future has been non-contact measurements. The idea is that you place your part in a measuring volume, press a button and voila, you get measurements that you can use.

In some cases that future is now. For example, take Industrial Computed Tomography (ICT), in some cases you CAN put a part inside the machine and press a button and get results. There are, however, some things to consider before you dive head first into ICT.

How does ICT work?

X-rays slice through the part which is on a rotary table and those X-rays are captured on a detector. The detector records the x-rays as a gray scale.

These 2D images are reconstructed into a 3D image, the individual points becoming 3D pixels or voxels.

These voxels form a point cloud which can then be output into a .STL file format or be used for NDT or dimensional measurements.

Here be dragons (or Chemistry and Physics)

The first questions customers usually ask is, “Will it measure my part?”. In response to that, we generally ask two questions, “How big is it?” and  “What is it made of?”. 

A colleague of mine in Germany, recently gave us a presentation where he explained the CT in relation to the periodic table. This cast the whole question of "can you measure my part" in a whole new light.  In general, ICT shines when working with elements up to element 10. It’s good with elements up to element 18. Element 29, CU, Copper is a demarcation line.

It is not prohibitive, but you need to start considering thickness, the material composition of the part, the various multiple materials etc. The amount of power needed to "punch" through the denser materials, the time it takes to scan the part all become variables to be considered.

In the cases of denser materials or multi materials, I think the best course of action is to actually try it and see if it works for your part. 

Simplest way to see if ICT works for you and your parts

The great thing that we offer is a free scan to see how our systems work with your parts and materials. If getting us a sample part to measure requires a NDA, (Non-Disclosure Agreement) we can execute this in fairly short order.

It doesn't cost you anything but the shipping to get results on one of your parts. It is only a matter of sending the parts to Wenzel America and for us to provide you with the results via a Web Meeting for fastest turnaround.

POC: Giles Gaskell
ADDRESS: Wenzel America 28700 Beck Rd. Wixom, MI 48393

ICT is great for non-destructive testing (NDT), but the magic that we spoke of earlier, the call to the future, was being able to have your part measured inside and out with features measured to nominals or a nominal to CAD comparison. Using a Wenzel CT will enable you to get reliable measurement results. In this case, the report you will receive will include the display of some of the NDT elements and a metrology report in either a traditional form, or via a graphical representation.

The future is now for you to see all of your part. Whether it is an assembly that you are checking for proper fit, or if you are checking for the dimensional data on some internal feature, send us your part now.

Use Computed Tomography to find your parts DNA.

CLAY MODELS – need a lift?

Clay models in a design studio are either mounted on posts/pins screwed into the cast iron or steel plate or on a lifter.

What are the pros and cons of the posts and the lifter?

First of all why do we need to raise the clay model?

1. The Z-axis stroke of clay mills starts way off the floor level
2. If we see from the guys working below the below-door or sill areas are hard to work on without the clay being raised up.

Point 1 cannot be argued with, although some vendors like Wenzel provide angle brackets to minimize the height of the dead milling area above the plate.

Looking again at the photo to the left, it’s clear to see that it would be even more convenient to work on the model if it was even higher up that shown here.

This picture shows the model mounted on higher
posts and it looks like the modelers have a good set up to work on the lower areas. I have heard designers say that the sill areas can have the least ‘style’ on the whole vehicle.

No modeler wants to work lying down on a cold steel plate for hours! If the model was mounted higher still, it would be even more convenient though.

This picture shows a model mounted in what would seem to be a convenient working height for the lower areas of the vehicle. This type of lifter (known as a scissor lift) provides an excellent range of Z-axis working heights.

This type of lifts are relatively cheap, but the Z positioning is not accurate so they are not compatible with automatic milling without the table height being recalibrated. Most are also perhaps not stable enough for high speed milling.

So if it’s important to have the model high enough so that modelers can give the sill areas the same degree of attention, why not just put the model on really high posts?

Two reasons why not

1. How can the modelers then work on the roof areas?
2. Most CNC mills don’t have a massive Z-stroke, so if the model is mounted too high milling operation cannot be performed on the roof areas either.

So what’s the answer?

Here is a new, driven lifter which was unveiled in the Wenzel Design Studio recently. Whilst this solution can be a little pricey, it offers massive benefits;

1. Manual (through a pendant) or automatic height adjustment
2. Repeatable and accurate positioning – mill - reset height –mill
3. Strong and stable telescopic legs for high speed milling
4. Quickly raise of lower for the most convenient working height for manual modelling
5. Lower completely to flush floor plate height for good studio aesthetics and easy cleaning

Need a lift? Let Wenzel help.

Andy Woodward
Wenzel America