Maintenance of mold for plastic optical lens

Mold maintenance for mold injection is mandatory. However depend on the manner, it may cause deterioration of quality and precision or cost and labor increment.

Dry ice cleaner "SUPERBLAST" enables proper maintenance with reduction of labor and cost without sacrificing mold quality!

Mold (Mould) of mold injection used for plastic (resin) lens production. Generally, a couple of maintenance mode are applied. One is outsourcing to mold maker, and the other is in-house cleaning. Both methods embrace issue of labor and cost.

Conventional method of mold maintenance

Outsource to mold maker

<Benefit>
Guaranteed quality
<issue>
× Troublesome for preparation and desk work.

In-house maintenance

<Method 1> Brushing
× Individual difference may cause damage to mold.
<Method 2>Sand blasting
×Dame to mold. Collection of blasted powder.

Practical application of dry ice blast cleaner "SUPERBLAST"...

Polyester resin is used for optical plastic lens as plastic material (type). The surface of mold for mole injection is mirror finished by Nickel (Ni) electro plating in order to enhance mold releasing. Also the surface of mold for plastic molding has a variety of complicated structure such as small hole, slit etc. Such precision mold is needed to maintain equivalent high precision as brand new mold even after cleaning for maintenance.

Our original dry ice blast cleaning system "SUPERBLAST" enables damage-free in-house cleaning of injection mold by applying unique method to blast crushed powder dry ice!

Dry ice blast cleaning of Ni plated mirror panel : Comparison of damage according to blasting method.

Pictures of Ni plating mirror surface after cleaning by different type of dry ice blast system.

Our SUPERBLAST does not damage mirror surface.

SUPERBLAST

Photo :Dry ice blast cleaning of Ni plated mirror pane by SUPERBLAST

Dry ice pellet dia. 0.3mm

Other dry ice blast cleaner

Photo :Dry ice blast cleaning of Ni plated mirror pane by others

Dry ice pellet dia. 3mm

Cleaning condition : Air pressure 0.5Mpa, time 5min, area 4cm2
*The image looks being distorted but it is due to reflection of fluorescent lamp.

Ra measurement result by DEKTAK(Surface roughness measurement)

  Before cleaning
(Unprocessed surface)
After cleaning
Gravity method
(Kyodo Int'l)
After cleaning
Direct pressure method
(Other maker)
Roughness 4 - 8 nm 44 - 8 nm Unmeasurable
Result - No change from
"Before cleaning"
Unmeasurable due
to large asperity.

 

Cleaning condition

  • Contamination : COP resin, Oil, Toluene taint
  • Status of mold : Ni electro plated (mirror finish) Surface temperature 120℃
  • Cleaned area : Asymmetric unlevel 300mm sq.
  • Cleaner : SUPERBLAST Reborn
  • Duration : 3min (one side), 6min (in total)

Result

  1. Visual inspection after cleaning
    No damage on surface was observed, so there were no damage on Ni electro plated layer (mirror finish).
  2. Inspection of produced lens
    No difference to mold serviced at mold maker, thus it was concluded that there were no damage to mold.
  3. Inspection of produced lens after aluminum coating process.
    Passed.
    *Stain and contamination are observed on the surface of aluminum layer if cleaning of mold is insufficient.