Volkswagen use WITNESS simulation to optimise manufacturing

Volkswagen Slovakia uses WITNESS simulation software from the Lanner Group to optimise new production and logistics systems. 

Background 

Given Volkswagen’s corporate goal to maintain its highly competitive position for new production, it is important that its key performance indicators such as low production costs, short throughput times, high quality and efficient production of model varieties are met. Requirements for production and logistics processes include; discipline in supply chain deliveries, low inventory levels, low capital allocation and fulfilling the planned production program.

VOLKSWAGEN SLOVAKIA, a.s. was founded in 1991 and now employs more than 9000 people and produces more than 280,000 cars, 330,000 gearboxes and 17million components a year. The company is based near Slovak’s capital, Bratislava.

Within the last two years, the Industrial Engineering Department of VW SLOVAKIA a.s. undertook several simulation projects aimed at optimisation of the new production and logistics systems using WITNESS, including:

• Simulation of the production plan and shift models for VW Golf, VW Bora and VW Polo production to minimise the work in progress (October 2001)
• Optimisation of the number of AGV’s that supply material baskets to the VW Polo assembly line (March 2002)
• Simulation of finalising tasks shop for the VW Polo with the aim of identifying weekly throughput depending on the frequency and type of defects in production (July 2001)
• Optimisation of the special inductance conveyor system serving the water test and final inspection zone (July 2002)
• Assembly line balancing (on-going)
• Optimisation of the number of AGV’s that supply material baskets to the VW Touareg assembly line (Oct 2002)
• Simulation of the conveyor system for transport of VW Polo and VW Touareg powertrains to the assembly line (August 2003)

One of the two projects can be described as follows:

The project is a simulation of a complex automated guided vehicle and load carrier system for material supply of the VW Touareg assembly line. The project duration was three months.The goal of the simulation project was to analyse the planned system and evaluate the following:

• Number of AGVs needed in relation to the planned throughput of the line
• Determine the traffic rules at the system junctions
• Determine priority rules at the system junctions,
• Vehicle breakdown analysis in different zones
• Find optimal parameters of the system (charging schedules, vehicle speeds in zones etc.)
• Determine the optimum initial AGV positions at the beginning of production week

Results

Simulation analysis identified a bottleneck in the AGV charging times and AGV speeds in manufacturing line replenishment zones.

Simulation experiments showed that with optimal settings of charging stations parameters and AGV speeds in system zones, it is possible to operate the system with 10% less than the originally planned number of automated guided vehicles.

After the commissioning of the whole production system, the simulation project results have been verified in real life. Simulation also showed that the initial AGV positions at the beginning of the production week, originally planned based on the static analysis, needed to be changed.