Using the two-part filament spool holder, it is examined which manufacturing costs arise in additive series production in 3D printing and how production in injection molding looks in comparison.
This comparison shows the machine hourly rates of the Multirap machines and thus offers insights into the amortization of the machines for your own applications.
It is very important that the costs of additive manufacturing are the same from a quantity of 1 and therefore there is no risk and no large storage.
Changes can also be implemented immediately and without additional costs. This is a very important point in the spool holder, since spools with different take-up diameters often have to be used and so changes occur frequently.

On the other hand, injection molding involves mold costs from the outset and large quantities have to be purchased.

The two-part spool holder for filament spools is used in Multirap devices to change the spools quickly and to hold them securely during the printing process.
It has a quick-release fastener that can be quickly released and closed with a quarter turn.

The reels weigh up to 3kg, there is no high demand for strength, but good impact strength and abrasion resistance is required.

Temperature resistance of up to 80°C is required, since the coils are also used in the heated filament room of the M800.

The component is very well suited for the FFF printing technology. The wall thicknesses are well dimensioned in all areas, so that very high strength can be achieved.

The degree of filling is selected with 25% infill, this low density optimizes the printing time with good strength.

Support material is not required, small overhanging areas (e.g. holes) and overhangs up to 50-55° can be printed without support material.

Material Temperature-resistant, impact-resistant Multec-PLA-HT

Multec PLA-HT is an in-house development with optimal properties for 3D printing. The material is food-safe, has a low tendency to shrink and very good thermal and mechanical properties (e.g. 40% higher impact strength than ABS, higher strength and heat resistance than PLA). PLA-HT can be sanded and painted very well.

Variant 1: Fine surface quality - €38.20 - Multirap M800

• Layer height: 0.2mm
• Number of perimeters: 2
• Fill level: 25%
• Printing time: approx. 6 hours for both components
• Weight (including support structure): approx. 100g for both components
• Material costs: approx. 4€
• With an average hourly machine rate of €5.70 (M800), this means total costs of around €38.20 for the bobbin holder.

Machine hour rates depending on depreciation and operating hours per year see Chapter 3 Cost Analysis.

Variant 2: Fast print - 19.70€ - Multirap M800

• Layer height: 0.4mm
• Number of perimeters: 2
• Fill level: 25
• Printing time: approx. 2h 45 minutes
• Weight (including support structure): approx. 100g for both components
• Material costs: approx. 4€
• With an average hourly machine rate of €5.70 (M800), this means that total costs of around € 19.70

One-time tool costs:

• Interchangeable mold frame EUR 6,200, -      
• Insert for filament spool holder short EUR 6,000, -
• Insert for filament spool holder long EUR 6,000.00

Total: €18,200

Graduated prices for production:

If one also considers liquidity and warehousing, an order of 1000 pieces immediately results in expenses of €38,560

Machine hour rate Multirap M500

On average, Multec customers have around 3,500 operating hours a year and depreciate the machine over 4 years. This results in a machine hourly rate for a Multirap M500 of 4,04 €.

The machine hour rates for other operating hours and periods of use can be found in the table below:

Machine hour rate Multirap M800

An average Multec customer has around 3,500 operating hours per year and depreciates the machine over 4 years. This results in a machine hourly rate for a Multirap M800 of 5,70 €.

The machine hour rates for other operating hours and periods of use can be found in the table below:

3D printing versus injection molding

The smaller Multirap M500 is assumed to have an average of 3,500 operating hours per year.
The second variant shows a Multirap M500 with 5,000 operating hours per year. Here you can see that injection molding has lower unit prices from approx. 700-1,000 pieces.

The larger Multirap M800 is assumed to have an average operating hours of 3,500 hours per year.
The second variant shows a Multirap M800 with 5,000 operating hours per year. Here it can be seen that from approx. 500-700 pieces injection molding proves to be a cheaper production technology.

Break Even Injection Molding – 3D Printing

As can be seen from the diagrams, injection molding proves to be a cheaper technology from 500 to 1000 pieces (depending on the machine and operating hours).

Below that, 3D printing is much more worthwhile, also from the point of view of liquidity and warehousing.

From a quantity of 1, the constant costs are 17-38€, whereas with injection molding an order of 1000 pieces immediately results in expenses of 38,560€

With the Multirap M500 and M800 devices, a series of 10-20 pieces can be printed in one printing process due to the large printing area.

With the continuous printing function, it is possible to produce without user intervention over a printing period of 60-120 hours, even over the weekend. This does not result in a reduction in production, but the operating time can be used 24/7.

With the operating hours of 3500 hours considered above, 1400 parts can be produced per year, so additive manufacturing can also be used very well from this point of view.