Science Buddies: "Ask an Expert"

I am a senior citizen (not student!) with a question I have never been able to find an answer to. I am hoping someone there can help. I have Googled it a dozen different ways. Here it is:

What happens to wood when a plank is sawed? What actually comes apart? Cells, molecules, atoms; what does the saw do to the wood besides make sawdust? How do particles separate?

Thanks!
Aliyah

The Ask the Expert forums are for students in grades K-12 who are working on hands-on science projects. There are other sites on the internet where your questions will be more appropriate.
Thank you,
Madeline
Science Buddies moderator