Demet Gönen

Scheduling Customized Orders by Considering the Ergonomic Constraints: A Case Study at YEMTAR Company

It is important for companies to meet customer demands by due date and reduce the labor cost on the finalized product. For this purpose, order scheduling is required for different purposes such as minimizing makespan, maximizing resource utilization, etc. Dynamic production environment causes stochastic operation times at companies which work based on project type labor-intensive production. Stochastic operation times make order scheduling harder. There are many reasons that causes operation times being stochastic such as technical specifications of the orders, skills of the operators, bottlenecks in the job-shop, and etc. However, one of the most important but less discussed constraints that affect the probability distribution of the operation times is the ergonomic constraint. Ergonomic constraints, such as musculoskeletal discomfort, fatigue and limitations determined by the laws make it even more difficult to predict the total makespan of waiting orders. In this study, an order scheduling algorithm that considers the dynamical production environment and the ergonomic limitations is proposed for nearly optimizing average makespan for several waiting orders in the grinding and painting workstation of YEMTAR Company. The proposed algorithm adopts the technical order specifications and ergonomic constraints together, computes the stochastic operation times by using simulation, and schedule orders by using genetic algorithm. The objective is to determine the entry sequence of the waiting orders to the workshop for minimizing their average makespan which directly influences the resource utilization, efficiency, and labor costs.

DEPOLAMA ALANLARINDA ÇALIŞANLARIN ÇALIŞMA POZİSYONLARININ İNCELENMESİ

Yuksek depolama alanlarinda calisan isciler siklikla yuksek raflara uzanmakta, bir platform olmaksizin yuksek raflara erisilmesi istendiginde bazen tirmanma hareketlerini yapabilmektedirler. Uzanma durumunda bel omurlarinda, kol ve omuz kaslarinda zorlanmalar meydana gelmektedir. Bu hareketin gun icerisinde siklikla tekrari halinde kas iskelet sistemi rahatsizliklari (KISR) olusmaktadir. Depo operasyonlarinda kol gucunun yogun olarak kullanilmasi sonucunda depo kazalari otomasyon sistemlerine gore daha riskli olabilmektedir. Calisma, otomotiv sektorunde kablo uretimi yapan bir isletmede gerceklestirilmistir. Isletmede ergonomik acidan uygun olmayan ve gun icerisinde tekrarlayan calisma duruslari gozlenmis ve bilgisayar destekli ergonomi yazilimi AnyBody Modelleme Sistemi (AMS) ile analiz edilmistir. Analiz sonuclari degerlendirilmis ve bu uygun olmayan, calisani zorlayan duruslarin giderilmesi icin onerilerde bulunulmustur. Amac, calisanin kas iskelet sistemini zorlayan calisma duruslarini onleyerek, olusabilecek is kazasi ve meslek hastaliklari riskini minimize etmektir. Calismanin amaci, calisanlar icin guvenli bir calisma ortami saglayarak, calisan memnuniyetini, urun kalitesini, uretim miktarini arttirmak ve uygun olmayan calisma duruslarinin yaratabilecegi maliyetleri azaltmaktir. Calisma sonunda calisanlarin guvenligini on planda tutacak istifleme ve depolama sistemleri onerilmistir.