Introduction

xFlex475 is a soft (50-60 Shore A), high-rebound elastomeric material suitable for grips, seals, or lattice foam replacement, etc. This is a low-viscosity material available in two colors (black and white). Because of very low green stiffness, xFLEX475 requires slow Z-axis movements. This material requires a unique post processing workflow to allow complete curing and avoiding a tacky surface. The material is normally tacky after washing, and a submerged curing is recommended.

Printing Tips

Keep the default Z-axis speeds and wait times for best results (at most conservative setting). If a user is trying to trouble shoot a print failure with this material, priority should be given to part orientation and support design.

Due to its soft and flexible nature, we recommend orienting parts with a short orientation to prevent swaying when peeling off the membrane. The material has similar consistency to a wet noodle when green.  A good rule of thumb is the build height should be no more than 2.5x the width.

Add cone supports (0.7mm contact width, >3mm base) around edges on any part that consume >50ml to withstand the peel forces and hold parts steady throughout a print. A very common cause of part defects are shift lines caused by parts swaying during the peel step. Having cone supports will allow parts to stay upright and will minimize them swaying to the sides.

Locate cone supports around boundary for larger parts to improve stability during printing

If the part has any amount of cupping (concave towards the membrane) a vent hole is required to prevent print quality defects. Take note to replace the plug and cure in place prior to application of mold release for submerged curing. 

Printing directly on the build platform will result in over cured base layers (elephant's foot) and stripes from slots in the build platform. Sanding or machining support nubs is not possible with xFlex475 due to the parts being very soft (similar to a rubber band), so close consideration is required when deciding which surfaces will require supports prior to printing. Avoid supports on surfaces used for sealing.

Post Processing

xFLEX will be tacky after washing and requires post-cure submerged in water. 

Validated Workflow

Support Removal

In most cases remove the supports prior to washing and curing to allow full access to the surface. Supports will remove more cleanly after curing, so leave 3-5mm of support material before the washing and curing, then trim close to the surface after curing.

Surface after ripping off supports - difficult to finish, better to leave a longer nub and cut with scalpel

Use a very sharp razor or scalpel, or very sharp cutters (we recommend cuticle snips used by beauticians). Reducing the part temperature can harden the part further and allow a cleaner cut. Snips will compress before cutting leaving a scar. Use a gentle sawing action with a scalpel is generally most effective.

Light sanding is possible on fully cured parts with adequate thickness; use an oscillating sander with very light pressure.

xFLEX475 sanded

Washing

xFLEX absorbs solvents when green. xCLEAN can be used for up to 1 min of cleaning, then rinse another minute in IPA, or just clean in IPA for 2 minutes. Use >99% pure IPA to avoid water absorption. Limit time in IPA to about 2 minutes total, use of ultrasonic (~24kHz) is recommended to clean complex geometry including lattice structures. The part will be tacky after washing due to solvent and/or water absorption. Leave the part to dry for 15-30 minutes.  Using saturated IPA is usually ok because any trace amounts of uncured material on the part will be cured in the next step.

Curing 

To avoid tackiness on the final part, curing should be done submerged to prevent oxygen from inhibiting the surface cure.

First, coat the part with a mold release such as LOCTITE® Frekote 770-NC or Smooth-On Universal Mold Release. If the part has a lattice structure and can't be fully sprayed, then submerge the part in mold release and allow to drip dry 15-30 min. The mold release prevents water absorption into the green part.

Next place the coated part in a clean, clear, borosilicate vessel (such as a baking dish or beaker), and fill water above the part. Use deionized water to eliminate the risk of hard-water stains, however tap water is acceptable in most cases.  

Cure in xCURE at room temperature for 30 minutes per side. Flip the part which will normally rest on the bottom of the glass vessel. Position the parts to get equal exposure to all sides.

Remove the mold release with clean IPA.

If there are any tacky surfaces, they can be addressed post-cure by application of talc.

Updated February 22, 2024 19:45