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The key elements of the FDM system include material feed mechanism , liquefier , print head , gantry , and build surface .
 material: elements; manufacturing process: FDM; engineering feature: material feed mechanism; machine or equipment: print head; process parameter: build surface
Please list all entity words in the text that fit the category.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} 
Answer:
 material: elements; manufacturing process: FDM; engineering feature: material feed mechanism; machine or equipment: print head; process parameter: build surface