Product

• Trendsetter NEWS
• Trendsetter Autoloader

Causes

1. Plates are damaged or bent. See Solution 1.
2. Image is imposed inverted and plates are not square from trailing edge to leading edge.
   
   If the work flow imposes the image upside down, it is not obvious which is the leading or trailing edge. The combination of inverted imposition and plates loaded in the bay upside down can cause an intermittent skew problem because the plates are intermittently not square from leading edge to trailing edge. See Solution 2.
3. Damage to the plate caused by the machine.
   See Solution 3.
4. Bender/punch combination is not in register.
   See Solution 4.

Note: Do not look at the side edges of the plate and state that because there is a slant to the image, or the gap at the top is different than the gap at the bottom, that this is a registration problem. The IMAGES on these plates will be in register on press 

Solutions

Case 1:

To determine if the skew is caused by plate damage, check a bad plate to determine if the bottom of the image is parallel to the leading edge of the plate:

• Measure and record the distance between the image and the bottom BEND on the left side.
• Measure and record the distance between the image and the bottom BEND on the right side.
• FLATTEN out the bend on the bottom edge with a hammer or block of wood and measure and record the distance between the image and the bottom EDGE on the left side.
• Measure and record the distance between the image and the bottom EDGE on the right side.

If these two sets of measurements are different, then a damaged plate may be the problem. Train the customer to look for ANY damage to the plate and to discard these plates, particularly BENT CORNERS (dog eared) or DENTS in the leading edge that line up with one of the Trendsetter's registration pins.

Do not rely on the customer to know whether the imposition is inverted.

To determine if the bottom edge is in fact the leading edge of the plate:

• Measure the distance between the image and the bottom edge of the plate on both sides.
• Measure the distance between the image and the top edge of the plate on both sides.
• If the distance from the bottom of the image to the bottom of the plate is NOT the same on both sides, and  the distance from the top edge to the top of the image is the SAME on both sides, then the trendsetter is mechanically functioning correctly but the image is being imposed inverted and the plates are also loaded in the bay inverted.

Inform and train the customer to load plates correctly.

• LECs: if the leading edge gap on both sides (1.4mm) and the middle(1.2mm) are too small the plate will enter the gap with slight friction. If the gap is too large, the plate may stand up on the lip of the registration pin on the drum.
• Plate's drop length should be 2 to 3 mm. PICK a plate then move the PICKER DOWN. Draw a line across the plate with a pencil guided by the leading edge clamps. Turn the PICKER VAC OFF then draw the line across the plate again. Take the plate out and check that the distance between the lines is 2 to 3 mm.
• Rest a plate on the drum pins and make sure there is clearance between the plate and the picker vacuum cups.
• If there is a dent in the edge of the plate around the registration pin, then look at the piece of foam on the side of the picker that prevents the picker down sensor from triggering too early. Any kind of shiny metal showing at the bottom of the foam piece may cause an intermittent premature plate drop since the flash of light may or may not be detected by the firmware since it only checks this sensor occasionally. Unpeel the foam and move it down. Error on the side of extra black foam sticking below the surface.
• A dent in the edge of the plate by the registration pin can  be caused when the plate drop is too small.
• Check that the plate is completely released be the suction cups and has settled on the registration pins before the leading edge clamp closes. The parameter, SET ALDLY PDP, for the delay change has a  default of 0.5, but  can be increased to 3 seconds. Note that changing this parameter directly effects throughput: on a 100 plate per hour machine, for every 1 second increase, you will loose 1 plate per hour through put.
• In more complicated conditions, a badly timed drum roller can cause a bubble in the plate as it is rolled onto the drum.

If the measurement from the bottom of a Bent plate to the bottom of the image differences from one side of the plate to the other, the bender/punch combination may not be in register. if it is not then the first suspect is the punch, in most cases the bender picks up off of the punch notches.

To confirm squareness of punch notches

• Take the out-of-register plate and flatten the bends if there are any.
• Take a "good plate" that is in register on press and flatten out its bends with a hammer or piece of wood.
• Place both plates on each other face up and place them in the trendsetter as if you are going to load them in manual bypass mode. Make sure that the leading edge is down.
• Shift the plates side to side until the TOP punch notches line up.
• Pull the plates out of the machine without letting them slide relative to one another and look at the BOTTOM punch notches. if they do not line up perfectly then the punch is failing to register the plates to our drum pin spacing on the correct side or it is not allowing the plate to settle on its pins before punching. If the notches do line up but bottom of plate to bottom of image does not measure the same on both sides, then it is the bender that is not registering correctly.
• Another test for punch registration that may or may not show a fault is to take one plate from the BOTTOM of a stack of 100 pre-punched plates and one plate from the TOP of the stack. Place these plates face up into the Trendsetter in manual bypass mode leading edge down. line up the TOP punch notches and remove the plates without allowing them to side on each other. If the bottom notches do not perfectly line up, then the punch is not using the trendsetter drum pin spacing or not registering on the correct edge.

Technical contact(s)

Scott Montague

Submitted by

Scott Montague

Date submitted

01 Nov 2001