8419
A printing processing window is defined following several requirements : a continuous deposit , without spreading in front of the printing head , maximum and minimum spreading pressures , an upper-limit for the separating force between head and substrate .
 printing head, pressures, force, substrate
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:
 printing head, pressures, force, substrate