Has the following query been made in the optimum way?
CREATE TABLE Manufacturers ( id int(11) NOT NULL AUTO_INCREMENT, 
name varchar(30) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB 

CREATE TABLE parts ( id int(11) NOT NULL AUTO_INCREMENT, name varchar(30) NOT NULL, 
man_id int(11) NOT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB


your structure looks OK for performance, because you have index the common field where you make the join on.  How ever, shouldn't you use PK and FK instead?.  If you need to know a bigger description use the explain command to be sure that the index are correctly used.