It’s possible a tough recession is just around the corner. As a roll forming manufacturer, you’re thinking about ways to avoid the pain. If you’re an Eclipse user, you can help your company by finally doing a full implementation of a system that allows you to improve capacity and margins without a lot of up-front costs. In fact, you’ve already paid the biggest cost when you bought the software. Continue reading “Re-implement Your Eclipse MES to Stave Off Economic Downturn”
You’ve implemented your new ERP with your state-of-the-art MES, and now you’re tracking problems on the shop floor! The MES has some cool reporting features, like built-in Pareto charts and drill-down capability.
After a few months, you check in with the Plant Manager. Are they using the new systems to get a better handle on issues? Well…it turns out the reports aren’t that helpful. Operators don’t like the system. The reports are full of charts and numbers, but the data isn’t meaningful to what’s happening day-to-day.
You know other companies use this system, and the word in the industry is that it’s really powerful. Trusted associates swear by the functionality. What could have gone wrong? I’ll tell you the three major areas where manufacturing companies fall down. Continue reading “Downtime Tracking and Data Bias”
The title of this post comes from a concept within Lean Six Sigma. It is a reflection of costs associated with scrap parts, wasted production time, and all the time, materials, and labor required to reproduce scrap in order to make enough good parts to satisfy a customer order, as well as the lost opportunities that come from the inefficiency and re-work. It encompasses all of the business processes that touch the manufacturing process, as well. From the order-taking and scheduling systems, to the method by which you bill your customers. Continue reading “The Cost of Poor Quality”
It’s the dreaded phrase we hear in manufacturing all the time – the bane of change management types. Even when it’s not actually spoken aloud, the mentality can be pervasive with Plant Managers, Operations Directors, and Owners. Continue reading “The How-We’ve-Always-Done-It Mentality”
In the world of Roll forming, length control discussions usually come down to, “Do we run an open loop or a closed loop system?” In some cases, both types of length control might be used on the same production line. Above, you can see two animated versions of the concepts depicted in examples of a flying die application, but both types are also available for feed-to-stop applications, as well.
Open or Closed?
For the most part, when someone talks about Open or Closed Loop, they are specifically denoting the presence of a servo system. The servo system is looking for a command to tell it what speed, direction, and position go to on a millisecond-by-millisecond basis. In this context, the controller tells the servo go here and the servo responds with feedback I’m there. Continue reading “Closed Loop vs Open Loop”
If you are a big manufacturer with a dominant place in the market – if you have hundreds of production lines – and if you have more capacity than you know what to do with, then this article isn’t for you. You can afford to be wasteful and sloppy. Improving margins might not be on your radar.
But if you are a small and scrappy manufacturer who’s looking for every edge you can get – keep reading… Continue reading “Downtime – The More Expensive Scrap”
When someone has a problem with length variance in roll forming applications, the prognosis is almost always encoder tracking. If you look at length control from the perspective of the computer that controls the process it’s the brains of the machine. It’s telling the roll former when to go and stop, and it’s telling the shear and punch when to fire. The encoder and wheel are the eyes and ears of the brain. Everything the computer knows – distance, speed, direction – all come from a very small contact point between the material and the encoder wheel. Continue reading “Length Variance and Encoder Tracking”
It doesn’t matter where I go – scrap is the form of waste most prominent in the minds of manufacturing companies. To my knowledge, steel is the material most roll formed in North America and around the world. In many companies the price of steel is a constant concern, because it can fluctuate wildly and it’s frequently the single biggest cost when it comes to calculating margin. I’ve seen companies make more money buying and re-selling coils than they could by turning that coil into finished product and selling it to their customers – at least when the market was particularly volatile.
I think the main reason companies focus on scrap is because it’s right there. You can see it, touch it, smell it, and weigh it. There’s a problem with the focus on scrap, because its usually not the biggest contributor to waste. Scrap is usually the third-biggest contributor to waste.
It’s important to note that I’m not saying you should ignore scrap or that you shouldn’t care about it. You should. In most roll forming applications, it should be relatively easy to hold scrap percentage to 0.5% or less. If you’re close to that value on your production lines, then you’re doing pretty well.
Speed-loss is usually a bigger contributor to waste than scrap. And the most common form of waste is downtime. If you have a lot of excess capacity in your plants, then downtime waste might not be an important concern for your company. If you’ve captured a lot of the market and your customers are saturated so that your Sales function cannot sell the capacity you already have, then you’re doing very well and this blog post might not be for you. If your company isn’t sitting pretty at the top of the heap, or if you’re struggling to find capacity without buying new equipment then you should continue reading.
If you’re setting up a punching operation with pneumatic or hydraulic presses, the servo feeds are relatively simple, because you have full control over the presses and when they’re fired. Mechanical presses running in continuous require a balance of timing and accelerations. If your timing is off, you could break tooling or miss your target. If your accelerations are off, the feed rolls could slip and induce a variance or even leave marks on the part.
Timing is directly impacted by production rate and press angle. The higher the rate, the faster the press has to run. The faster the press runs, the more acceleration you need to make servo moves. Ultimately, production rate is capped by the capability of the press motor/drive and the maximum acceleration rate of the servo motor.
The most efficient way to dial in a particular production line is to setup the servo to handle the most extreme production rate and minimize setup changes for less-demanding applications. The demands of production – balancing speed, quality, wear, and cost – might require a unique set of parameters for every job a line might run. This post will walk through the math of using press speed and part/punch distance to calculate the speeds and accelerations required from the servo.
Unless you’re using a servo, press consistency is crucial to length accuracy in flying punch and cut applications. Without servo positioning, timing variances in the press will directly relate to length tolerance error, and the faster you run the line, the worse even small timing variances will affect length.
For instance, if you’re running a roll former at 400 fpm, that’s 80 ips. At that speed a timing variance as small as ±0.003 s will cause a total length variance of ±0.24″!
Even the best 24 VDC relays have a switching time of ± 0.003 s. Thus, running a press fire output through an electro-mechanical relay could easily induce a total length variance of almost 0.5″. That assumes you have no encoder tracking issues.