Method for manufacturing a preform for a wind turbine blade

A method of manufacturing a part for a wind turbine blade, the method comprising the steps of

• providing a mould (90) comprising a mould surface,
• fastening one or more channel members (72) to the mould surface, each channel member (72) having a longitudinal axis, an inner surface (75) and an opposing outer surface (76),
• laying a fibre material (85) and optionally a binding agent on the mould surface (87),
• covering the fibre material, the optional binding agent and the one or more channel members with a vacuum bag, and
• applying negative pressure to the fibre material and the optional binding agent via the one or more channel members for consolidating the part,
• wherein each channel member (72) comprises a plurality of slits (77) extending between its inner surface and its outer surface, the slits having an orientation that is substantially transverse to the longitudinal axis of the channel member.