Decorative lace production has been highly mechanised since the 19th century. Modern lace is
manufactured on CNC Jacquard and Raschel looms, little technological development has
occurred since the early 1980's. Decorative lace is knitted in webs as much as 3.8m wide
containing may smaller lace breadths. The lace breadths must be separated from the main
web ready for garment manufacture. The separation process for decorative lace is
traditionally carried out using scissors or a guided knife system. The development of a
machine vision guided laser cutting system at Loughborough University in the 1990's
demonstrated that an economical fully automatic cutting system could replace the slow and
expensive traditional methods. Marketing of the laser cutting system has identified some
weaknesses in the quality of the cut-edge for some markets that require higher quality lace.
The vision-guided laser cutting system utilises a continuous wave (CW) laser. Incorrect
positioning of the laser causes melting to the lace edge which can be detected by a rough
A high accuracy pulsed laser-cutting solution for lace is demonstrated in this thesis. The lace
is cut by applying a short pulse of laser energy directly onto individual threads that connect
the lace breadth to the waste material. An edge directed algorithm that utilises a transmissive
illumination method locates the position of the cutting point on the threads. The transmissive
illumination method highlights lace density as well as position. The density information
facilitates the accurate location of the lace-cutting path.
A 3D transient finite difference thermal model of the cutting process has been developed to
aid in the optimisation of the laser process. Deficiencies in the existing CW process have
been highlighted with the model. Optimum processing parameters have been calculated with
the model for the pulsed process.
Fully automatic, vision guided, pulsed laser cutting of lace has been demonstrated on a low
speed system. The lace produced on the pulsed laser system has been shown to have a
significant improvement in edge quality over lace produced using the CW process. The edge
quality approaches that of traditionally cut lace.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.