The material handling industry as a whole seems slow to change compared to other sectors. In ten years, the tech sector reduced the social appeal of that super cool flip phone you once bragged about in favor of the ability to unlock your new smartphone with facial recognition software just so you can book an Uber ride to head across town for a brief Saturday gathering with friends.

If you’re not paying attention, it can seem like the material handling industry cannot keep up with the times and then one day you look up only to realize you just got out of the DeLorean. Well, welcome back to the future, or should I say the present, if you have been asleep all of these years.

What is 24 Volt DC / MDR Technology?

Conveyors have been around for centuries. Although their first market appearance is difficult to pinpoint, you can trace their place in the modern industrial space back to Ludwig Roselius in 1907. 

24 Volt DC, MDR Drive Roller
24 Volt DC, MDR Drive Roller

Growing up in America, we cannot forget Henry Ford, the titan of the industrial industry. Ford implemented the production line around 1913, and conveyors played in reducing the time it took to assemble a vehicle by a factor of eight.

Fast forward to today, where I struggle to convince my friends and family with no knowledge of this space that there has been anything resembling massive innovations and that conveyors do more than move forward in a straight line. 

The 24 Volt DC Conveyor or motor driven roller (MDR) conveyor is one of the most impactful innovations in the industrial industry. From what we know, this started in 1975 when Mr. Kazuo Itoh, the President of Itoh Denki, changed the conveyor world forever by introducing the AC motor driven roller. In 1988, the conveyor transformed into a 24 Volt DC motor driven roller. Since then, the conveyor has experienced many iterations in technology advancement that are still highly effective to this day. 

What Makes MDR Different From These AC Motorized Conveyors?

Typical AC Motor Belt Conveyor
Typical AC Motor Belt Conveyor

The major differentiating characteristic is the motor’s location. The motor is inside the tube of a roller! In other words, the motor is self-contained within the roller itself. The most common size roller tube diameter when conveying boxes that are 100 lbs. or less is a 1.9” diameter roller, and yes MDR packs a 24 Volt DC motor inclusive of a gearing package inside of this very roller.

In MDR conveyor terms, we refer to this roller as the drive roller. This drive roller has a power cable coming out of one end that you plug into what we refer to as a “drive card” or “control card”, which is the brain that has total control over the drive roller. The exciting part about this control card is that a lot of the logic needed to program the control card is pre-packaged in the card itself when it arrives from the manufacturer! 

Additionally, we add a photo-eye or sensor that is also plugged into this control card. Lastly, we use bands or O-rings to connect this drive roller to carrier rollers that are ahead (downstream) and behind (upstream) of the drive roller. Let’s say there are four carrier rollers downstream and four carrier rollers upstream. These are now referred to as your “accumulation zone” or “zone” for short. Whew! I know that was A LOT of information, but here’s where it starts to get fun.

Setting up the Card Manufacturer Logic

24 Volt DC, MDR Zone
24 Volt DC, MDR Zone

Remember when I said the control card has pre-packaged logic? Well, we need one last piece of hardware to bring this to life. There is a typically very generic 6-pin communication cable (similar to a phone cable) that is used to plug into one control card and then that same cable plugs into the downstream zone. Then there is another communication cable that plugs into the upstream zone. Card manufacturer logic is now ready to see the light of day and bring this conveyor from explanation into reality (assuming you have powered the conveyor). 

Conveyor Zones

Let’s say this conveyor has four zones that are each 27” in length, which means the overall conveyor is how long? If you answered 9’-0”, then you received extra credit! So, let’s say we place a box that is 15” long on the first conveyor zone. You will have the pleasure of watching this box convey downstream all the way to the end of the line and then it will stop. 

Now you put a second box on the line. This box is flowing downstream and it stops in the second to last zone and does not hit the box ahead (downstream) of it! So how exactly did this conveyor with absolutely no programming know how to do that!? We certainly didn’t do anything special to make this happen. Remember a while back when we connected each of the control cards with communication cables? These inexpensive, standard cables, act as the link to send messages between the cards after receiving feedback from the photoeyes (sensors) that report back to the card whether they are blocked (i.e., the product is in the path of the sensor) or clear (i.e., the product is NOT in the path of the sensor). 

Through this information, the second box we put on knows to stop in the zone upstream (behind) of the first box. We can do this until we have all four boxes on the line. This technology where boxes or products accumulate but do not touch is known as “zero pressure accumulation”, or ZPA for short. So now that you are an expert on what 24 Volt DC and MDR conveyors, let’s discuss the various applications that accentuate the many benefits of this not so new, yet seriously underutilized technology.

24 Volt DC, MDR Conveyor Typical Wiring Diagram
24 Volt DC, MDR Conveyor Typical Wiring Diagram

What Are the Advantages of MDR Conveyors?

Laying out a conveyor system is not about picking “the best” type of conveyor. There are pros and cons to every type of conveyor, so it becomes critical to select the most appropriate type of conveyor specific to your application. 24 Volt DC MDR Conveyor has many applications where it makes sense. I’m going to ask you to use your memory one more time, and recall one of the newest terms in our vocabulary.

Zero Pressure Accumulation 

That term is zero pressure accumulation or ZPA for short. This is the most common reason to use a 24V DC conveyor. For instance, you may have a pick and pack operation or an order fulfillment system, but you want some buffer factor in the unloading process to minimize the backup of your transportation conveyor. Think 24vdc conveyor for the end of your line. 

You may want an accumulation buffer when receiving boxes off your brand-new high-speed sorter. Think 24vdc conveyor. I could go on and on, but you get the gist. MDR conveyor is best suited for zero pressure accumulation applications. While there are other types of conveyors that can offer ZPA, 24vdc MDR conveyor is truly the premium option for several reasons.

Easy Maintenance

For starters, your maintenance team is going to thank you many times over for reading this blog. Say good-bye to complicated pneumatics and air bags forever. The modular nature of MDR conveyors makes the maintenance much simpler. The simplicity of doing maintenance is truly a game-changer, and it will reduce your down time relatively speaking when you do encounter the need to replace a component.

Reduces Energy Consumption 

Another likely possibility is that your energy provider may start to wonder if 80% of your business decided to take a month-long vacation. If that analogy went right over your head there is no shame. In layman’s terms, you will see a reduction in energy consumption vs the more traditional 460v / 3ph motor conveyors. 

One of the benefits of the MDR conveyor is that each zone is only on when the product is either present in a zone or if the upstream photo eye is blocked. A zone will also stay on briefly after a product is downstream of that zone. The result is massive energy savings since your conveyor is only active when the product is running.

Easy Installation 

Lastly, we can point out that the ease of installation makes implementation a walk in the park. Aside from all of the aforementioned components, you only need a 24vdc power source to see this in action. There are no belts to track, motors to wire, VFD’s to program, or any other tedious tasks. This is why we say that MDR is “plug and play”. There is a time and a place for the other style conveyors. However, when you have a zero-pressure accumulation application, need an accumulation buffer, or want to install a shorter run, the 24 Volt DC MDR conveyor is a solution you will not regret considering.

Need a 24 Volt DC / MDR Conveyor?

Material Handling Technologies, Inc. (MHT) is best known as a highly innovative conveyor systems integrator. However, we are also an OEM of MDR conveyor technology. Thanks to our knowledgeable, skillful engineering and fabrication teams, we have kept our quality high, lead times low, and prices just right. We would love to hear from you if there is an upcoming project to discuss or if you have some general questions we can help answer. Give us a call at 1-800-779-2475 or contact us via our website, and check out our 24 Volt DC Stealthzone™ Conveyor.

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