Injection Molding

תכנון הנדסי לאופטיקה פלסטית מוזרקת

Angular mapping aspheric lens used in a  line camera. FOV: 90o, resolution:20u

תכנון רכיבי אופטיקה פלסטית מוזרקת

A double injection line camera designed for automatic assembly. Over 100,000 units of this design were manufactured



Injected plastic components  have two main advantages:
• adaptability to mass production (low cost, high throughput)
• ability to manufacture the housing together with the optics

CSTM R&D Solutions has acquired accumulated experience in developing and implementing optical packaging projects using custom injected plastic parts. We undertake plastic optic projects from concept to mass production. Our strength is in giving a complete QC backing to the process until the required yield is obtained. Our involvement starts at the optical design and prototyping stages, and continues in perfecting the process itself, and in realizing the tools necessary in the processing stations. Such manufacturing tools may include active alignment jigs, bonding and clamping jigs and test jigs of various kinds.

Development Steps
Plastic optics development includes the following steps:
• Conceptual design
• Preliminary optical design
• Preliminary optomechanical design
• Performance analysis (stray light, tolerances, manufacturability)
• Critical design
• Machined prototype (often skipped)
• Production tools and injected prototypes
• Pilot rounds – tune process until a sufficient output yield is reached.
• Ramp up

 Realization Tolerances
In general injected plastic optics can reach the following accuracy levels, where at least half of the deviation is due to process repeatability problems:

• dR/R (relative radius deviation):  0.5%
• Surface profile deviation [um]: 0.6D2/R and no less than 1u/inch
where: R is the radius of curvature of the surface in mm
D is the outer diameter of the surface in mm
• Angle between element surfaces: 10u divided by the insert width
• Centering error (shift of surfaces in respect to each other): ~20u
• External dimensions: approximately 20u



Injected plastic elements – pros & cons



• 20 -100 times cheaper than glass components
• High production throughput
• Integrated packaging, easy to assemble
• Aspheric optics – for about the same cost/pc
• Adaptability to combine elements (Freeform)
• Double injection technique
• dealing with birefringence effect (defocus, scattering)
• high moisture absorption content
• high Coefficient of thermal expansion
• high Thermal coefficient of refractive index
• haze – Stray light scattering  from surface and volume
• a small range of low refractive index materials
• low working temperatures
• vulnerability of plastic optical surfaces
• relatively low working temperature
• low adhesion
• simple coatings
• the need to stabilize the injection process