German Agricultural Equipment Supplier × Honscn Precision: 5-Axis CNC Machining Fixes Hole Alignment for Tractor Front Motor Pulley Gears

About customers: A trusted brand in the German agricultural machinery industry

Our customer, located in Bavaria, Germany, has been manufacturing agricultural equipment for 80 years. They are well known in Europe for their rugged and reliable tractor parts, especially those that can handle harsh environments such as muddy fields and steep hills. Their front motor pulley system is an important part of their product line, and more than 30% of high-end tractors in Western Europe use this system.

This project focused on a critical gear in the front motor pulley of a tractor. It is the component that transfers the power from the engine to the pulley, so it needs to be strong enough to withstand constant heavy use. The customer needed to be able to:

• Withstands forces up to 800MPa (this is the strength of their specified material 42CrMo5 steel)

• Keep the two small holes on the side perfectly positioned (within 0.03mm of where you want them)

• Reliable operation in the field, whether it is extremely cold (-40°C) or hot (80°C)

Problems we face: tricky holes and drawing confusion

(1) Hole alignment problem

It is important that there are two holes on the side of the gear. The customer's specifications are as follows:

• One hole (let's call it hole A) needs to be located exactly in the gap between the two teeth.

• The other (hole B) must be perfectly aligned with the tooth tip

But when our team reviewed the drawings, we realized something was wrong. If we followed the measurements exactly, the holes would be off by 0.2 millimeters. That might sound small, but it meant that hole A would overlap the root of the tooth, and hole B would miss the tip of the tooth—definitely bad for how the pulley connects to the motor.

(2) Use hard steel

42CrMo5 steel is ideal for this type of gear because it is very strong, but it is difficult to machine. Drilling such a precise hole? We knew we would encounter the following problems:

• The tool wears quickly – 60% faster than when drilling softer metals

• Rough edges inside the hole, which may cause the gear to crack over time

• When we drill near a tooth, the hardened surface of the tooth (which has been specially treated) can chip.

How we solve this problem: Smart repair and precision machining

(1) Fix the drawing first

As soon as we noticed the hole alignment issue, we immediately took action. Our engineers:

• Make a 3D model of the gear to check the hole positions

• Found a tiny angle error on the drawing (should be 72°, not 70°)

• The specs were redrawn and sent to the client – they approved the changes within a day so we didn’t waste time

(2) Use 5-axis CNC to achieve correct processing

We used a five-axis CNC machine (DMG MORI DMU 50, extremely high precision) to ensure that all parts were aligned neatly. The specific operations are as follows:

First, we prepare the steel:

• We heat and cool the metal (a process called normalizing) to ensure it is consistent—no soft or hard spots that could affect drilling.

Then, for the hole:

• We drilled in steps: first a small pilot hole, then a slightly larger hole, and finally one more time to make the edges smooth (so it doesn't break later)

• Maintain a moderate drilling speed—1,200 rpm for roughing and 800 rpm for finishing—to avoid overheating the steel.

• Use a special clamp with soft pads to hold the gears so we don't scratch them while we work

Finally, we checked everything:

• The hole position is measured with precision instruments from Zeiss to ensure an accuracy of 0.005 mm

What Happened Next: Excellent Results and Happy Clients

(1) The equipment meets all requirements

(2) What did the customer say?

Their Production Manager Markus Schmidt told us: “We were concerned when we saw the errors on the drawings, but Honscn quickly resolved them. The gears fit our pulleys perfectly – we tested them for 300 hours straight without any issues. They even delivered the samples to us a few weeks earlier than we expected.”

After ordering the first 500 gears, they ordered another 2000. Now they are negotiating new projects with us, such as producing lighter gears for their next tractor model.

Why this is important for agricultural machinery

This project shows how we help agricultural equipment manufacturers build better parts. For gears like tractor pulleys that work hard every day, precision is critical. Whether it’s fixing a drawing error or drilling a complex hole using a five-axis machine, we ensure parts are durable, accurate, reliable, and ready for the field.