It seems to be a daily question when customers call ProtoCAM for a quote: “How do you price a stereolithography prototype?” or “What are my options for reducing the cost of my part?”

Stereolithography parts are priced using 5 criteria (in order of importance):

1. Overall height of the part - Most parts are built using a .004” layer thickness. The exception is a high resolution build which uses .002” layer thickness. The 3D file is “sliced” into layers and then traced and solidified layer by layer on the SLA machine. Consequently, a 6 inch part (1500 layers) will take longer to build than a 3 inch part (750 layers) and therefore, cost more.
2. Volume of the part - This relates to the number of cubic inches of material that will be needed to make the part. Again, the larger the part the greater the volume of material needed and the greater the cost.
3. Complexity of the part - When the part is finished on the SLA machine, it will require time to have the excess resin removed as well as having the support material removed. The prototype is then post cured in a UV oven and bead blasted to provide a consistent finish over the entire part.
4. Finish level of the part - ProtoCAM offers several levels of part finishing ranging from an economy “strip and ship” to a “presentation” level. Our standard level of finish requires the removal of supports with some light sanding on the support surfaces with an overall bead blast prior to shipping. See our Stereolithography Prototypes page to see our offerings of various finish levels.
5. Lead time of the part - ProtoCAM’s standard lead time is 2 days after receipt of order. Some parts, due to size, require a longer lead time. If you need your prototype part sooner, there is an additional charge to accomplish that requirement.

Understanding the above criteria can make the answer to the second question “What are my options to reduce the cost of my part” seem a lot easier.

Height of Part
Since the biggest contributor to cost is the overall height of the part, the simplest way is to either orient the part with a smaller z height or cut the part in half and allow us to glue it together prior to shipping.

Volume
Reducing the volume to cut the part cost can be accomplished by “hollowing” solid pieces or reducing wall thickness on thick walled parts.

Finishing
If a “presentation” level piece is needed, it can be the customer’s option to perform that work. An experienced customer knows that it can take several hours (or days) to completely sand a stereolithography part, but because of timing or cost the customer may choose to do that work themselves.

Lead Time
The easiest way to reduce part cost is to increase the lead time. If the customer doesn’t need the part within 2 days, increasing the lead time to 1 or 2 weeks will also cut the prototype cost.

Number of Prototypes Ordered
If multiple copies of the prototype may be needed, it is highly recommended to purchase those with the initial run of parts. Economies of scale come into play here and the greater the quantity ordered the smaller the per piece cost.

ProtoCAM will generally orient the part to give the customer the best quality within the shortest amount of time. But if other options need to be explored to meet scheduling or budget constraints, we recommend calling us at 1-800-408-9019. Just ask for the project manager that quoted your project (name can be found in the upper left hand portion of the quote) and we will be glad to explain options that are available to meet your requirements.

Ray Biery
ProtoCAM Managing Partner

Labels: prototypes, rapid prototyping, stereolithography