Ali Oral

Computer-assisted robotic tiling of mosaics

This paper describes the development of a system that is capable of tiling mosaics using a robot according to requirements of the individual customer. The art of mosaic, in one form or another, has been practiced manually for thousands of years. Modern developments in materials and production techniques could be found as evidence that mosaic is very much alive in the new millennium. It is very costly and also difficult to find skilful people to tile mosaic. Therefore a computer-assisted robotic system has been constructed and applied. To activate the system a particular algorithm has been developed and successfully applied on an available SCARA robot.

Patterning automation of square mosaics using computer assisted scara robot

Today mosaics are used as decorative elements both indoors and outdoors. Mosaics can be obtained by combining small pieces of stone, glass, wood and glazed tiles together to make some picture and illustration. Mosaic-making processes are carried out manually for thousand years. Complexities involved in piece selection, surface detection and mould fitting have limited the automation of this process. In this work, software that makes the mosaic patterning process automatic is developed. For this purpose, software named SMT V2 has been developed to obtain different mosaic patterning. The software also tested with experimental applications by selective compliance articulated robot arm (SCARA) robot on real environment using different shaped marble pieces and successful results are obtained.

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.

Surface roughness analysis of greater cutting depths during hard turning

Abstract Literally, hard machining describes machining of parts having hardness over 45 HRC. Besides its advantages like high metal removal rate, easiness of adapting to complex part geometries, possibility of dry cutting; this operation, which can substitute grinding in most cases, has some disadvantages. One of them is the significant increase of surface roughness due to tool wear even when the tool life limit is not exceeded. In this study, considering hard turning praxes, higher depths of cut (0.5 to 1.0 mm) were examined when dry turning AISI D2 cold work tool steel, through-hardened to 62 HRC. TiN coated mixed ceramic inserts (Al2O3 + TiCN) were employed in the operations. Relationship between surface roughness and cutting parameters (cutting speed, feed and depth of cut) was modeled and analyzed using a Box-Behnken response surface methodology (RSM) design. A linear model best described this relationship. Despite the higher depths of cuts, the surface roughness values achieved were comparable to those in grinding operations. Finally, the optimal values of cutting parameters for minimum surface roughness were predicted.