JOURNAL OF COMPOSITE MATERIALS Article An experimental study on milling of natural fiber (jute)- reinforced polymer composites Yahya H C ¸ elik 1 , Erol Kilickap 2 and Ali _ Imran Kilickap 1 Abstract The interest in materials having natural, environmentally friendly, renewable and low density/cost is increasing day by day due to sanctions imposed to reduce the emission rates, especially the Kyoto Protocol. In recent years, the use of environmentally friendly composites by using natural fibers such as flax, jute and sisal has increased in engineering applications. Milling operation has frequently been an important method of machining which can achieve the desired dimensions and tolerances for the plate-shaped parts. In this study, the effects of cutting parameters such as cutting speed and feed rate on cutting force, delamination factor and surface roughness in end milling of jute fiber-reinforced polymer composite plates with different orientation angle (0  /90  , 30  /60  and 45  ) were examined by using the cemented carbide (WC) end mills (two, three and four number of flutes). Cutting force, deformation factor and surface roughness were found to be influenced by the feed rate and cutting speeds. In addition, increasing the number of the flutes of the cutting tools reduced the cutting force, delamination factor and surface roughness. Keywords Composites, cutting force, delamination, end milling, jute, surface roughness Introduction Researchers and engineers constantly study the fiber- reinforced polymer composites because of their unique advantages, such as high strength to weight ratio, abrasion resistance and high fracture toughness. 1 Petroleum-based synthetic fibers are used in polymer composites due to their high strength and hardness. 2 Glass fiber-reinforced polymer composites have been widely used for many years due to their low cost and good strength advantages. 1 However, these fibers have serious disadvantages due to high initial processing costs, difficulties in recycling, high-energy consumption, adverse effects on the natural environment, and danger to human health and the environment, etc. 3 When syn- thetic composites consume their life, their separation is very difficult by the conventional methods, because the components are very tightly connected to each other and relatively stable, and therefore, it is difficult to sep- arate and recycle. In aircrafts such as Boeing 787 and AIRBUS 350 that are developed in recent years, com- posites are used as a structural component. The rate of these composites is more than 50%. Recycling is a serious problem after the end of the life of composite parts. Recently, the development of recyclable and environmentally sustainable composite materials has gained importance due to environmental awareness in the world. Therefore, material producers take environ- mental impacts into account, and they produce envir- onmentally compatible materials at all stages of their life cycle. 1 The impact of global climate change has been quite visible in recent years depending on the increase in greenhouse gas emissions. 2 Interest in nat- ural, environmentally friendly and renewable materials has been increasing steadily to reduce the greenhouse gas emission rates because of the sanctions imposed. To reduce the emission values, the use of natural fibers with low cost and high strength/weight ratios in the automotive industry has been widespread since they 1 Department of Mechanical Engineering, Batman University, Turkey 2 Department of Mechanical Engineering, Dicle University, Turkey Corresponding author: Erol Kilickap, Department of Mechanical Engineering, Dicle University, Diyarbakir, Turkey. Email: ekilickap@dicle.edu.tr Journal of Composite Materials 0(0) 1–11 ! The Author(s) 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0021998319826373 journals.sagepub.com/home/jcm