The Grand Tour of German Automotive—Daimler Truck Wörth

Daimler Wörth Aerial Photo
Mercedes-Benz Wörth aerial photo

The last plant of my visits to Mercedes-Benz  as part of my Grand Tour of German Automotive, was not a car plant, but the world’s largest heavy-duty truck plant, in Wörth (albeit it is technically a separate company, not Mercedes-Benz but Daimler Truck). Seeing three parallel heavy-duty truck assembly lines popping out a truck every minute is quite impressive. And it is one of the few instances where they actually use an Exoskeleton for work rather than merely to impress others. Read on!

Disclaimer: The following is based on my personal observations and opinions and may not be accurate or correct. It is based on publicly available information and what I observed during public tours, and when I observed it. The observations may differ at a different time and place.

Introduction to Mercedes-Benz Wörth Truck

The Mercedes-Benz Wörth Truck plant started producing trucks in 1963 and has 10 000 employees. It is the largest heavy-duty truck plant in the world, producing up to 470 trucks per day, with around 70 000 trucks produced per year. This includes some CKD (completely knocked down) assembly kits for countries where assembly in the country is tax beneficial. The plant produces Arocs, Atego, and Actros trucks.

Mercedes-Benz Unimog assembly

There is also a second plant-within-a-plant on the same location for special trucks such as Unimog, Econic, and Zetros. This second plant produces up to 20 trucks per day and is more of a manufactory than an assembly line. It has its own development, and tours will be possible in the near future.

All trucks are made to order. Each order creates a separate order for the cabin and the undercarriage, which are produced separately and later joined together in a process called Hochzeit (marriage). Pre-assembly takes place on the ground floor, while final assembly takes place on the second floor.

The plant has an interesting indoor testing track with a wind tunnel. There are also plans for a future eTruck that can be fully charged in 20–40 minutes. The plant operates on two shifts, from 5:45–14:15 and 14:30–23:00, with Saturday being a maintenance shift. The plant is not as clean as Audi and VW, but it is better than BMW Berlin Bikes. Only 5% of the workers are female. To help employees get around the huge plant, they also provide 2000 bicycles.

Welding of Cabin

We first visited the welding of the cabin. Almost all body shop work is done through spot welding, with each spot taking 4 seconds to complete. There are 550 variants of the driver cabin, and 4 welding cells are available, each capable of handling any cabin variant. These cells usually have no light, as they are operated only by robots.

Automated Guided Vehicles (AGVs) are used for material transport to the line and also for carrying the cabin to some welding cells. These AGVs have been in place since 2002. I have seen AGVs for vehicle bodies before for passenger cars and motor bikes, but this was the first time for me to see this in truck production.

The lead time for the welding process is between 9–14 hours, with an average of 11.5 hours. The takt time per cabin is 4:30 minutes. All trucks are checked and measured inline, with 2% undergoing even more measurement offline, with up to 900 measurements being taken.

Paint Shop

We did not visit the paint shop, but compared to cars it has significantly more color options. Where normal mid-range cars have something like 10–30 color options, these cabins had 450 color options available. While a car buyer just wants a nice-looking car, for trucks it is often part of their corporate identity. The overall lead time of the paint shop was 8 hours.

Assembly of Cabin

The assembly of the cabin at the Mercedes-Benz Wörth Trucks plant is a complex process. Most of it is manual work, except for the assembly of the front windshield. This rather heavy part is installed by two robots. The seats are delivered just in sequence (JIS) with only a twenty-minute notice.

While most assembly lines measure their speed in time per product (a takt), here they measure the line speed in meter per minute. During my visit this was 1.38 m/min. As always, I also estimated the percentage of value adding work, which was 44% (see my blog post How to Estimate Value Add for Manual Work for more). This is on average with German automotive assembly lines… but this is a truck assembly line. Trucks usually have more variety, and 44% is actually a tad better than 41% for trucks at Mitsubishi Fuso in Kawasaki and another confidential truck line at 40%.

The assembly line is divided into 127 assembly groups, with each group consisting of 15–20 employees. Within the group there is a group leader (wearing a light blue shirt), a quality responsible (wearing an orange shirt), and a quality alarm (wearing a red shirt) if there are imminent quality problems. Interestingly, the roles of the group leader, the quality responsible, and the quality alarm are re-assigned every week by the operators in the group themselves. Kind of a democratic way for a bottom-level leadership. Five to six groups are led by a team leader.

Underbody work using an Exoskeleton (not Mercedes-Benz)
Underbody work using an Exoskeleton (not Mercedes-Benz)

The assembly line uses a moving platform, but there is one slot where the cabins hang from a rail system for work underneath the cabin. This is one of the very few instances where I have seen the use of an Exoskeleton. This mechanical assist reduces tired arms during assembly work under the truck.

The assembly line uses flexible manpower line, with the speed adjusted to the number of people present. The model mix is also taken into account. The lead time for cabin assembly is 8 hours. As with cars, the doors are removed before assembly for easy access.

Assembly of Undercarriage and Marriage

The assembly of the undercarriage and the merger with the cabin is done on three parallel lines. The actual merger is—just as with cars—called a marriage (Hochzeit). Before that, the undercarriage is initially positioned upside down for easy assembly and to avoid overhead work. As with cabin assembly, there are lots of options, and an undercarriage has around 2000 different options.

In automotive, a lot of the assembly line consists of moving platforms. Here, they did not have moving platforms. Instead, in the center was a chain driven line that pulled the undercarriages and later the entire truck forward. The employees, however, had to walk along the line while assembling the car. At one spot was a manually pushed platform that moved along with the line for one station and then was pushed back by hand. This was somewhat similar to the platforms I saw in Rastatt, albeit in Rastatt they were on a moving platform, whereas Wörth did not have a moving platform.

Daimler Wörth Assembly Side Cars
Mercedes-Benz Wörth assembly side cars

The speed of the line was 1.4 meter per min on one line, and 1.51 meter per min on the second line. On average, each of the three lines has a takt of three minutes per truck. The lead time for the entire process, from sheet metal to truck, is 65 hours. I also estimated the percentage of value add of the operators, which was quite good at 47%. That is better than most German car assembly lines except BMW, Porsche Taycan, and Mercedes-Benz in Rastatt. It was the most efficient truck assembly line that I have seen (so far).

During the marriage of the cabin with the underbody, a plastic bag is placed under the doors of the cabin to catch any dripping rust prevention sealant. Before, this was always a problem with messy spills. This idea was suggested by an employee, who received a sizeable bonus of EUR 100 000 for it.

Daimler Unimog
Mercedes-BenzUnimog

After assembly, the trucks undergo a driving test on a rolling test stand, which rolls a power generator and produces electricity. The heat generated during the test is also recycled. The batteries for electric trucks like the eActros are assembled later, due to their weight and the need for a high-voltage expert (Hochvolttechniker).

This completes my visit to the four Mercedes-Benz plants in Sindelfingen, Bremen, Rastatt, and Wörth. However, the Grand Tour of German Automotive is still far from over. In my next blog post I will continue with the Volkswagen group, starting with their Porsche brand plants. Now, go out, discover new ideas in other plants that can improve your own, and organize your industry!

PS: Many thanks to Daimler for offering tours through their plants to the public!


Discover more from AllAboutLean.com

Subscribe to get the latest posts sent to your email.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Cookie Consent with Real Cookie Banner