Dear Laxmi,
The use of a continuous feeder vs a pile feeder can be based upon the following criteria.
1. What is the run length, volume, of the work? IF you have extensive run lengths or if all sheets are similar in size, a continuous feeder is best. If you have short run lengths of 5000 to 20,000, you can use a pile feeder.
2. What is the sheet size? If you are creating a 32 page signature and you ahve the 102 press, I am assuming the sheet size is large. It is better to use a continuous feeder for this because you may need to "break" the sheets when loading them on the feeder to insure that they do not stick together due to ink coverage in areas. A continuous feeder requires the sheets to be broken, shingled and loaded to insure this. A pile feeder may not insure this unless you obtain a feeder that has an excellent sheet separateion system.
YOur paper weight of 45 to 120 gsm is a fairly light to a medium weight stock. THe 45 gsm may give you more issues due the the possibility of wrinkling and curling.
In regards to a knife vs a buckle folder. there are distinct advantages to both. A knife folder uses less floor space and can handle bulky folds. A knife is limited to the amount of folds that can be made and may not always provide as tight of a fold as a buckle folder can for signature work. A knife may also be a fixed design in the center of the machine and may limit you to not be able to perform folds that require scoring or perforating in the preceding folding machine station when these operations are required. Be careful to also to see if the knife can be positioned to fold from the top down or from the bottom up to match your impositions.
Buckle folding machines offer more imposition possibilities and better sheet control. YOu can adjust roller tensions to create more pressure and can select from normally 4 fold plate positions to create numerous impositions. It is better to create a double gatefold on a buckle folder than on a knife folder due to setup time. It is also better to use a buckle folder for double gatefold folding when you place a roillaway right angle folder in the next position to be used as a pressing station. If you have a knife type machine, you cannot due this.
Best regards,
Mark Pellman