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First , both the surface roughness and minimum processing margin of the O-LHAM sample were reduced to 20 % of the WAAM sample , because the droplet transfer was stabilized by the laser-arc synergic effects .
 surface roughness, sample, WAAM, sample, droplet
Please list all entity words in the text that fit the category. Output format is "word1, 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:
 surface roughness, sample, WAAM, sample, droplet