Method and apparatus for manufacturing bobbins

A method of manufacturing a bobbin made essentially or partially of a curable resin, comprising the steps of:

• a) providing a mold having a male portion and a female portion, the male and female portions together defining a gap of the shape and dimensions of the bobbin, the mold being provided with a resin inlet and vacuum port in communication with the gap, said female portion having a grooved inner surface, grooves on the grooved inner surface being a mirror image of grooves to be produced on a surface of the bobbin;
• b) laying on a surface of the male portion of the mold, or winding thereon, an element or material;
• c) inserting the male portion of the mold into the female portion thereof and securely connecting the two portions, when connected, being essentially sealed against pressure loss along their contact surfaces;
• d) causing a curable resin to flow into the gap through the resin inlet and around the element or material which is on the surface of the male portion, while applying a vacuum at the vacuum port, until an empty space provided within the gap is substantially entirely filled with resin thereby embedding the element or material within the resin;
• e) allowing the resin to solidify to produce the bobbin having grooves;
• f) subjecting the mold to a heat treatment which results in a temporary difference in the expansions of the materials constituting the mold and the bobbin, the heat treatment being applied so as to facilitate separation of the bobbin from the mold;
• and
• g) separating the bobbin from the female portion and/or the male portion while separation is facilitated due to the heat treatment.