OPAC seminar, June 15th, 2017

By: processindustrylab

June 15, 2017 - June 15, 2017

3:30 pm – 4:30 am


Joost de Kruijff MSc and Bram Westerweel MSc

Joost de Kruijff MSc

Integer programming models for the mid-term production planning of high-tech low-volume industries

We studied the mid-term production planning of high-tech low-volume industries. Mid-term production planning (6 to 24 months) allocates the capacity of production resources to different products over time and coordinates the associated inventories and material inputs so that known or predicted demand is met in the best possible manner. High-tech low-volume industries can be characterized by the limited production quantities and the complexity of the supply chain. Our MILP models can handle general supply chains and production processes that require multiple resources. Furthermore, they support semi-flexible capacity constraints and multiple production modes.

First, we introduce a model that assigns resources explicitly to release orders. Resulting in a second model, we introduce alternative capacity constraints, which assure that the available capacity in any subset of the planning horizon is sufficient. Since the number of these constraints is exponential we solve the second model without any capacity constraints. Each time an incumbent is found during the branch and bound process a maximum flow problem is used to find missing constraints. If a missing constraint is found it is added and the branch and bound process is restarted. Results from a realistic test case show that utilizing this algorithm to solve the second model is significantly faster than solving the first model. Our current research focusses on further improving this algorithm.

Bram Westerweel MSc

On-site additive manufacturing of temporary spare parts

In recent years, additive manufacturing (AM), also known as 3D printing, has developed rapidly. A promising application of this technology comes in the form of on-site and on-demand printing of spare parts. However, given the current limitations of AM technology, printed parts are often subject to a lower reliability compared to their regular counterparts. Therefore, we investigate to what extent this on-site AM capacity can complement, or even replace existing means of resupply. We consider a periodic-review spare part inventory control system with three supply sources. Regular supply of spare parts is done via resupply shipments every so many periods. In between these shipments, shortages of spare parts can be met either by expediting a regular part or by printing a part with a lower reliability. We characterize the optimal inventory control policy and find that in between regular shipments, there first exists an interval in which regular parts are expedited, then an interval in which parts are printed, and finally a period in which backorders are incurred. We investigate the operational cost reductions that can be attained by on-site printing of spare parts, and conclude that having access to on-site AM capacity leads to significant cost reductions, even when printed parts possess a much lower reliability than the regular spare parts.

Location: TU/e, Building Paviljoen, F9.                                          Feel free to join, if you are interested!


Event Location

Eindhoven University of Technology