Most conveyor systems on most production lines have conveyor transfer plates, i.e., stationary surfaces of roughly 6” that products have to cross to get from one conveyor to another. For good reason, these are also known as dead plates.
For some applications, the conveyor transfer plates are there because historically they were the only option. As an example, for many years in the pharmaceutical industry, the only way to have small vials change directions was to push them over a dead plate and around a turn disc.
For many applications, conveyors with dead plates are common simply because that’s how conveyor manufacturers make them. The bearings and motors that drive the conveyors are mounted on the outside of the equipment, which prevents the conveyors from lying flush against each other. Many of these manufacturers can make equipment without conveyor transfer plates, but it’s not their specialty and the machines are typically more expensive.
Every time we visit a manufacturing facility, we see the myriad problems that dead plates cause — problems that dig into productivity and profits. That’s why we make all of our conveyor systems without dead plates.
Here are some of the dead plate pitfalls we’ve observed.
Downtime (and lost throughput) caused by product instability
The biggest problem with dead plates is that the products that go across them frequently fall over. This is because the only way for a product to move across the dead plate is to be pushed by the product behind it.
For highly stable products, like cans of beans, this design works just fine. But it doesn’t work for products like lightweight plastic containers, small vials, or top-heavy wine bottles. When these products collide, they’re likely to fall over, which means someone has to stop the line and pick them up.
If this happens even once an hour (a conservative estimate) the productivity losses can add up significantly. Let’s say you run just one 8-hour shift/day (another conservative estimate) and it only takes 1 minute (also conservative) to shut the line down, right the fallen products, and get the line running again.
8 minutes/day x 5 days/week = 40 minutes
40 minutes x 52 weeks/year = 2080 minutes = 35.67 hours/year
That’s almost a week’s worth of productivity lost every year due to conveyor transfer plates alone. There are many other causes of downtime, and they can’t all be avoided. But this one can!
When products collide or fall over, they can become damaged. Again, this isn’t so much of a problem with cans of beans, but it can be a massive problem with glass bottles or vials.
Glass can straight up break, which makes a mess and gives rise to some of the other problems on this list. But there are even worse possible outcomes of glass-to-glass contact, namely, microfractures can occur and products can become contaminated with glass particulate. Both of these problems are associated with using glass vials for pharmaceutical products — microfractures can cause the vials to shatter in doctors’ hands, and glass particulate is responsible for about 20% of drug recalls due to foreign matter contamination.
Slower-than-desired line speeds
Manufacturers across industries are looking to increase their line speeds to boost throughput in their current footprint. But, as lines move faster, the collisions that happen to move products off of the dead plates get bigger. That means more products falling over, which exacerbates the problems described above.
Dead plates limit your line speeds. Like with downtime, they aren’t the only limiting factor. But they are a limiting factor. Fortunately, unlike some of the others, this factor is easy to eliminate with better conveyor design.
Another way dead plates negatively impact productivity is that at the end of a run, there will always be products left on the dead plates — no other units came down the line to push them across. So, you’re always left with products stranded on the dead plates that employees have to push through manually.
High labor requirements
Finally, related a couple of the previous points, if you’re like most manufacturers, you’re having trouble finding and keeping workers to run your machines. With labor in short supply, the last thing you need is for employees to be spending their time babysitting the transfer points.
Eliminating dead plates is an easy way to reduce labor requirements on your line.
So, how many of these occur in your plant?