Due-date assignment and job-shop scheduling optimization at Mackenzie Atlantic Tool & Die Machining Ltd.

Mackenzie Atlantic Tool & Die Machining Ltd. is a precision machine shop that operates with both manualand computer numerical control (CNC) machines, providing manufacturing service for the aerospace, marine,military, and oil and gas sectors. One of the most difficult aspects of the shop is to manage scheduling. Due to ahigh volume of order requests, arriving at a random rate, the shop floor flow is always changing toaccommodate the priorities and due-dates. Currently, there is no system for taking into account different factorsthat contribute to a scheduling system. Examples of this factors are; Machine Capacity, Spindle Utilization,Optimal order quantity, Change orders, and customer/order priority.In job shop environments the variance of order flow time is relatively large due to resource constrains and theiravailability to serve the orders. This availability is impacted by current work-in-process and future orders' duedates. Models that consider order's requirement of the resource, and other orders and work-in-process arerequired to assign due-dates or to plan shop flow properly to meet the due-dates.The scheduling part of the problem is a total weighted tardiness job-shop scheduling problem in which there iscertain number of jobs to be processed by a certain number of machines (stations) in a pre-known order. Eachjob has a due-date and a weight attached to it. The weight identifies the job or costumer's priority. The job-shopscheduling problem is a strong NP-hard problem hence a heuristic method will be needed to address thisproblem and its variations.Our ultimate objective is to integrate a due-date assignment problem and a total weighted job shop schedulingproblem optimization. The inputs of the model are the current jobs (with their status and assigned due date) anda set of new jobs that need to be scheduled. The objective of the model is to minimize the weighted tardiness ofall current and new jobs.