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However , there are still no specific standards available to label the quality requirements of the parts produced by WAAM and this is preventing a more widespread adoption of the technique.A crucial step towards the quality assurance of WAAM parts will be the development of Non-Destructive Testing ( NDT ) systems capable of identifying defects while parts are being produced .
 standards, quality, WAAM, step, quality, WAAM, be, Non-Destructive Testing, NDT, defects
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:
 standards, quality, WAAM, step, quality, WAAM, be, Non-Destructive Testing, NDT, defects