How to Parallel Your Roller Mill

It’s essential to keep the rollers in your mill parallel to each other. At RMS, customers often ask why they need to parallel and zero their rolls and how to complete this task.

First, it’s important to note that these are two different processes. The first is the actual paralleling of the rolls, making sure they are equal distances apart at all points. The second process, the zeroing, makes sure you have a known point where the faces of the rolls would touch if they’re at zero.

Here, we walk you through how to calibrate a roller mill for even wear and optimal performance.

Why It’s Important to Parallel and Zero Your Rolls

There are a few crucial reasons for paralleling and zeroing the rolls on your roller mill.

Remember that you’re trying to keep a consistent grind profile. If your rolls are out of parallel, meaning one side is open more than the other, you’re going to get uneven grind size. This can affect your micron sizing and your deviation, which ultimately affects your final product.

Being out of parallel with an even roll gap will also create uneven wear on the rolls. When the rolls are not parallel, one set will be working harder than the other, causing irregular wear that can jeopardize their performance and longevity. The parallel and zero process can help maximize your roll life.

When rolls aren’t parallel, they can also cause uneven motor load amps, which decreases equipment efficiency and causes problems like overheating and reduced output quality.

Parallel a Roller Mill in a Few Simple Steps

Before getting started, it’s important to know that anytime you’re moving the fine adjustments on your mill, you always want to make sure that the lash (the mechanical advantage) is always moving in. When you make any small adjustments, if you’re moving in, you can keep moving in. If you ever have to back it out, bring it one full revolution open and then bring it back in.

Start on the left side or the right side of your mill, and move each roll in individually. Each roll has a dial next to it with hash marks, each mark representing a thousandth of an inch. The big numbered hash marks show ten thousandths of an inch increments. Turn the dial clockwise with your wrench to move the roll in. Turn the dial counterclockwise to back the roll out.

Calibrating the Rolls

Calibrating the rolls on your mill is crucial for maintaining consistent and accurate milling results. Proper calibration ensures that the gap between rollers is set to the desired size, resulting in uniform particle size distribution and efficient milling performance. A well-calibrated roller mill prevents excessive grinding or uneven milling, which can lead to wasted materials and lower product quality. Regular calibration also helps in optimizing energy consumption and extending the lifespan of the mill by ensuring even wear, ultimately enhancing overall production efficiency.

To calibrate the rolls, follow these steps:

1. Take a wrench and move the roll in slowly until you hear the rolls start to rub against each other. You may need to move the roll past zero before you hear this sound. If this happens, turn the dial back counterclockwise toward zero.

2. While the rolls are still touching, turn your wrench counterclockwise, open up the roll one full revolution to zero, and then bring it back clockwise to the ‘5’ on the dial. Bringing it back to the five keeps your rolls at a known point for the zeroing process.

3. If the rolls are parallel, you will hear them touch around the zero mark. If they’re not, keep doing this process. Typically, you’ll need to do this process two to three times on both the left and right sides of the roller mill to ensure parallel rolls. Remember, there needs to be even gaps between rolls to ensure uniform size reduction during the milling process.

How to Zero Your Roller Mill

Now that you know how to parallel a roller mill, it’s time to learn about the zeroing process. It is important to slowly walk the rolls in because you’re not sure how far away from the face of the roll each of them is. Once you walk them in, you can set the zero.

Follow this five-step process to zero your roller mill:

1. Walk your rolls in five thousands of an inch at a time on each side until you reach the ‘2’, or twenty-thousandths mark. The goal here is to set the zero point. As you start to move the rolls in, they’re most likely going to hit before the zero.

2. Count how many hash marks from your known point (the ‘2’ on the dial) before a roll starts to hit. You’ll hear a ticking sound when this happens. Go slow for this process as you move the dial closer to zero and keep track of the hash marks.

3. Once you know your distance away from the ‘2’ mark, move the dial up one revolution again, turning counterclockwise. Then, come back to the ‘2’ mark and slowly move the dial toward the hash mark where the rolls started to hit on your previous round.

4. Do the same thing on the other side of the mill. As long as your rolls stay parallel, they will hit about at the same spot on the dial. If your hash mark was eight marks away from the ‘2’ on the dial on the right side, the same should be true on the left side, give or take one hash mark.

5. To verify they are parallel, bring the dial back toward zero until you hear the rolls hit. This way, you know that your rolls are both now parallel and zero from each other. Now, you can set your grind profile to whatever you need to get the grind profile you’re looking for and get an even particle size.

FAQs About the Parallel and Zero Process

Is it a problem if my rolls touch when paralleling them?

No, it’s not a problem for the brief amount of time they will touch during the adjustment. They are really tough and won’t get damaged. However, if you were to rub the rolls together for an excessive amount of time due to uneven gaps between rolls, you would start to wear them.

I think I hear the roll touching, but I’m not sure–what could be happening?

The rolls could be touching, or it could be the V-block. The V-block sits on the end of the roll and keeps the material from getting out the side of the roll. When the rolls are rubbing against the V-block and not each other, the noise is more of a high-pitched whistling sound. When you hear rolls touch, it’s more of a low rumbling sound.

How often do I need to parallel a roller mill?

This is highly dependent on the raw material you’re grinding. Tough or fibrous materials will wear out the machine faster, which means that you’ll need to calibrate the rolls more often. Remember, the parallel and zero processes are a regular part of roller mill maintenance. Our technicians can help you decide how often to adjust your machine for optimal performance and even wear.

Why do I need to calibrate the rolls on my mill?

Calibrating, or paralleling, the rolls on your mill ensures an even grind, proper machine performance, and reduces the risk of uneven wear and the need for a premature roll replacement. It also supports energy efficiency and prevents overheating.

Have More Questions About How to Parallel a Roller Mill? Contact RMS Today!

RMS Roller-Grinder is dedicated to helping our customers extend their roll life with proper roller mill maintenance. We aren’t in business to make a sale and disappear–we are your partner whether you need support now, tomorrow, or years down the line. Let our experts assist you with your parallel and zero process–contact us today.