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A difficulty thus arises in the post processing of these components as volumes within the part have differing material properties by definition and will therefore exhibit variable machinability.In this study , machining of functionally graded Ti6Al4V/ WC components consisting of a metal matrix composite ( MMC ) region and a single alloy region produced via direct energy deposition using commercially available tooling is explored .
 concept or principle: post processing; machine or equipment: components; material: as; concept or principle: material properties; manufacturing process: machining; concept or principle: functionally graded; material: WC; machine or equipment: components; material: metal matrix composite; material: MMC; material: alloy; manufacturing process: direct energy deposition; concept or principle: tooling
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
 Entities: post processing, components, as, material properties, machining, functionally graded, WC, components, metal matrix composite, MMC, alloy, direct energy deposition, tooling 
Answer:
 concept or principle: post processing; machine or equipment: components; material: as; concept or principle: material properties; manufacturing process: machining; concept or principle: functionally graded; material: WC; machine or equipment: components; material: metal matrix composite; material: MMC; material: alloy; manufacturing process: direct energy deposition; concept or principle: tooling