SMED yöntemi kullanılarak kalıp hazırlık sürelerinin azaltılması = Reducing mold preparation times with SMED method

Abstract

Yalın Üretim Sistemi, sonsuz insan ihtiyaçlarını karşılayabilmek için kıt kaynakların en verimli şekilde kullanılmasını ve zorlu rekabet koşullarında satış fiyatını arttırmak yerine, maliyetleri minimize ederek kar marjını arttırmak suretiyle rekabet edebilirliğini geliştirmeyi hedefler. Yalın üretim prensiplerine göre kaynakları daha verimli kullanabilmek için; tek parça akışın sağlanması, stokların azaltılması ve küçük partilerle üretimin gerçekleştirilebilmesi son derece önemlidir. Bu hedeflere ulaşılabilmesi için işletme önündeki en büyük engellerden birisi de yüksek hazırlık/model değişim süreleridir. Yalın Üretim Sisteminde hazırlık/model değişim sürelerini azaltabilmek için kullanılan en önemli tekniklerden biri Tekli Dakikalarda Model Değişim (SMED-Single Minute Exchange of Die) tekniğidir. Bu teknik, makine hazırlık sürelerindeki kayıpları etkili bir şekilde azaltırken, iş güvenliği risklerini düşürür ve ergonomik çalışma koşullarının iyileşmesine olanak sağlar. SMED yıllarca süren deneyim ve çabaların sonucunda ortaya çıkan ve yalın üretim felsefesinin fabrikalarda uygulanabilmesi için gerekliliği en önemli tekniklerden biridir. Sürekli değişen müşteri taleplerine tam zamanında cevap verebilmek için her fabrikanın tezgah ve operasyonlarında SMED tekniği uygulanabilir. Bu çalışmada; Sakarya'da faaliyet gösteren ve alüminyum profilden kış bahçesi, kapı pencere, balkon kaplama ve korkuluk sistemleri üreten bir alüminyum doğrama fabrikasında geciken sevkiyatları en aza indirmek ve yalın üretimin prensiplerinden birisi olan tek parça akışa bir adım daha yaklaşabilmek adına SMED yöntemi uygulanmıştır. Mevcut durumun analizinde Değer Akış Haritası (DAH) kullanılarak SMED yöntemine göre ilk analiz yapılmıştır. Mevcut durumun tespitinin ardından ECRS (Eliminate, Combine, Rearrange, Simplify) analizi uygulanmıştır ve belirlenen iyileştirmeler devreye alınmıştır. Çalışma sonucunda ilgili tezgahtaki hazırlık süreleri %66 azalmış, ilgili üretim alanında parti büyüklükleri %62 azalmış ve tezgahın OEE (Overall Equipment Effectiveness) oranı %9,7 artmıştır. Çalışma sonucunda elde edilen bilgiler ışığında Yalın Üretim tekniklerinin birbiriyle bütünleşik olarak kullanıldığında, üretim etkinliğine pozitif yönlü etki ettiği belirlenmiştir ve bu bütünleşik yaklaşımın işletme içerisindeki diğer alanlarda da yaygınlaştırılmasına karar verilmiştir.

The Lean Production System aims to use scarce resources in the most efficient way to meet endless human needs and to improve its competitiveness by minimizing costs and increasing profit margin instead of increasing the sales price in tough competitive conditions. In order to use resources more efficiently according to lean production principles; It is extremely important to ensure one-piece flow, reduce stocks, and produce with small batches. One of the biggest obstacles in front of the business in order to reach these targets is the high preparation/model change times. One of the most important techniques used to reduce the preparation/model change times in the Lean Manufacturing System is the Model Exchange in Single Minutes (SMED-Single Minute Exchange of Die) technique. This technique effectively reduces losses in machine setup times, reduces occupational safety risks and allows for improved ergonomic working conditions. SMED is one of the most important techniques that emerged as a result of years of experience and efforts and required for the implementation of lean production philosophy in factories. SMED technique can be applied in the workbench and operations of each factory in order to respond to the ever-changing customer demands in a timely manner. In this study; Delayed shipments, high inventory cost and long set-up time caused by the accessories produced in the accessory manufacturing department of an aluminum joinery factory operating in Sakarya that produces winter garden, door, window, balcony cladding and railing systems from project-based aluminum profiles. SMED method has been applied in order to minimize the problem and to get one step closer to one-piece flow, which is one of the principles of lean production. In the first stage of the study, product families were determined for the product to be drawn with Value Stream Map. Determined product families were grouped into routes and cycle herds, and the product with the highest production number among them was selected to draw the map. After the determined product group, the Value Stream Map was drawn and bottlenecks were identified on the map in order to determine the pilot study area. After the identified bottlenecks, the retrospective 1-year OEE values of the relevant selected press machine were examined in detail according to three parameters: the number of die change on a monthly basis, die change time on a minute basis and the rate of die change time in OEE. In order to select the mold on which the SMED method will be applied, the changed mold type, number of changes and change time parameters were examined and the mold to which SMED would be applied was determined. In the analysis of the current situation, the first analysis was made according to the SMED method using Value Stream Map (DAH), and the set-up combination table was created and the process was measured as 24.2 minutes. In line with the data on the table, the actual time is divided into 14.7 minutes of internal set-up and 9.5 minutes of external set-up. After determining the internal and external set-ups, improvement activities are planned to transfer the internal set-up work elements to the external set-up work elements. In line with these activities, the 5S technique, which is an effective lean production technique, has been applied. After the 5S activity, the die change, which was made as an operator in the current situation, was increased to 2 operators. In this way, the preparation time was measured as 14.4 minutes after the measurement and 68% improvement was achieved. After the current situation was determined, ECRS (Eliminate, Combine, Rearrange, Simplify) analysis was applied and the determined improvements were put into use. As a result of the ECRS analysis, a total of 22 items were improved, resulting in 6.38 minutes of savings. After the implementation of all SMED techniques, the current number of set-up steps, which was 98, was reduced to 79 in the last case. As a result of the improvements made, in order to standardize the SMED Kaizen work and ensure its continuity, the list and description of the adjustment activities to be made by the team leader before the current mold changes are created as "Mold change pre-preparation instruction" and "Mold change instruction", and the improvement work is recorded in the corporate memory of the company. was done. In this way, it is prevented that the improvement steps determined as a result of the habits that will change are overlooked by the operator. Value stream map applications do not show physical location. However, it was observed that there was a problem in the physical location in the current situation map drawing. As determined from the spaghetti diagrams in the current layout, it has been determined that the storage areas occupy a lot of space and the distance between the benches that should be close to each other is also an obstacle in the transition to flow type production. As a result of the analyzes made, the machines that have a more intense relationship with each other (material flow) were compared one by one and positioned closer to each other. After the new locations created, according to the layout, an annual distance of 654,566,4 meters was achieved from the material run-off distances due to the material flow, and 43.6% from the material stock areas. One of the important improvement points identified in the value stream map was the use of mass manufacturing technique in the current situation. Mass production was causing problems such as high lot sizes, high intermediate stocks, inability to take quick action against fast reactions from assembly lines. In order to prevent these problems, Kanban work was started in the accessory manufacturing department as a pilot region. Supermarkets were fed according to the amount of material determined by placing supermarkets between the lines. In this way, assembly line downtimes due to lack of material in production decreased by 45%. The intermediate stock amount, which was stated as 750 units and 2.2 days in the current situation value stream map, was reduced to 285 units and reduced to 0.83 days. As a result of these improvement activities implemented, the effectiveness of the study was measured and analyzed with six-month OEE data. In this direction, the improvement targets set at the beginning of the study were successfully achieved. As a result of the study, the preparation times in the relevant machine decreased by 66%, the lot sizes in the relevant production area decreased by 62% and the OEE (Overall Equipment Effectiveness) rate of the machine increased by 9.7%. The approach discussed in this study, together with the techniques of lean manufacturing philosophy (Value Stream Mapping, SMED, 5S, Kanban, Kaizen), has contributed to the literature that improvements can be made in different areas so that it can be applied in an integrated way in businesses. Studies should always start with the rejection of the current situation and work should be done to improve the situation. Increasing the competitiveness and profitability of businesses is based on the continuity of this perspective. Thus, contrary to the traditional production approach, businesses will be able to obtain the desired part and process quality at lower cost compared to their competitors.