Introduction: Two Mainstream Technologies, Two Different Cost Logics

In the world of 3D printing, SLA (Stereolithography) and SLS (Selective Laser Sintering) are the two most widely used industrial technologies. SLA excels at high‑precision, smooth‑surface appearance parts; SLS requires no supports and produces durable nylon functional parts. However, many engineers focus only on equipment parameters when choosing a process, overlooking the huge differences in cost structure. This article uses a real part case study to deeply analyze the cost components of SLA and SLS from the perspectives of material cost, machine time, post‑processing, batch effects, and more, helping you make a more economical decision.

Chapter 1: Case Part Introduction – A Typical “Dilemma”

We selected a representative part – a small drone housing measuring 120×80×45mm, wall thickness 1.5mm, with internal ribs, cooling grilles, and an internal curved air channel (an undercut feature), plus four mounting bosses on the bottom. The part requirements were:

• Dimensional accuracy: ±0.15mm
• Surface quality: smooth appearance, no visible layer lines
• Material: good toughness, impact resistance, heat resistance ≥80°C
• Quantities: two scenarios – 10 pieces (small batch prototype) and 100 pieces (small batch production)

The internal curved air channel is an undercut feature. SLA requires complex supports that cannot be fully removed, while SLS can print it in one piece without supports. This fundamental difference determines the viability of the two processes.

Chapter 2: SLA – Cost and Performance Analysis

2.1 SLA Cost Breakdown (10 pieces)

• Material cost: Standard SLA resin ~¥0.5/g, part + supports ~45g → ¥22.5; supports add ~30% consumption → actual ¥29/piece.
• Machine time cost: 10 pieces printed together in 6 hours; machine depreciation+labor+power ~¥60/hour → ¥36/piece.
• Post‑processing cost: Cleaning, support removal, UV curing, sanding → ¥20/piece.
• Total cost per piece: ¥85.

2.2 SLA Strengths and Limitations

• Strengths: Surface roughness Ra1.6-3.2μm, as smooth as injection molding; accuracy ±0.05-0.1mm; transparent parts possible; lower cost.
• Limitations: Supports required; removal may damage part; resin is brittle, poor impact resistance; low heat resistance (typically 50-60°C); tends to yellow and absorb moisture over time; the internal air channel’s supports cannot be removed → SLA cannot produce this part at all.

Critical issue: For the internal curved air channel (undercut), SLA supports cannot reach it. Forcing the print would leave support residue inside the channel, impossible to clean. Therefore, SLA is actually unable to make this part.

Chapter 3: SLS – Cost and Performance Analysis

3.1 SLS Cost Breakdown (10 pieces)

• Material cost: Nylon PA12 powder ~¥0.4/g, part consumes 45g, utilization 75% → ¥24; small batch requires fresh powder → actual ¥30/piece.
• Machine time cost: SLS equipment depreciation higher (~¥150/hour), 10 pieces in one build takes 5 hours → ¥75/piece.
• Post‑processing cost: Powder removal, blasting → ¥12/piece.
• Total cost per piece: ¥117 (38% higher than SLA).

3.2 SLS Strengths and Limitations

• Core strengths: No supports needed – can print undercuts, internal channels, living hinges, etc.; Nylon 12 material – excellent toughness, impact resistance, fatigue resistance; heat resistance 80-100°C; good dimensional stability, low moisture absorption; matte finish suitable for functional parts.
• Limitations: Surface roughness Ra6-12μm, matte texture (less smooth than SLA); expensive equipment, higher material waste, higher small‑batch cost; cannot print transparent parts.

Key advantage: The internal curved air channel can be printed without any supports in SLS, leaving a smooth internal surface for smooth airflow – something SLA simply cannot achieve.

Chapter 4: Cost and Feasibility Comparison at Different Batch Sizes

Core conclusion: For this part, because of the internal undercut air channel, SLA simply cannot make it, no matter how low the cost. SLS is the only feasible 3D printing process. This reveals the primary principle of process selection: Feasibility > Performance > Cost.

Chapter 5: In‑Depth Analysis of Key Factors Affecting Cost and Selection

5.1 Geometric Complexity – SLS’s “Moat”

SLS’s greatest value is “no supports required”. For internal channels, undercuts, spiral structures, living hinges, etc., SLS is often the only choice. Even if SLA costs less, it’s meaningless if the part can’t be made. In real projects, about 40% of SLS orders are chosen because SLA/CNC cannot handle the complex geometry.

5.2 Material Properties – SLS’s “Irreplaceability”

SLA resins are typically brittle, with elongation at break of only 5-15%, while SLS nylon can reach 20-50% and offers excellent fatigue and impact resistance. For parts that endure repeated loading (clips, hinges, drone arms), SLS lasts 5-10 times longer than SLA. Using SLA as a substitute could cause the part to break during testing.

5.3 Post‑Processing Difficulty – SLA’s Hidden Cost

SLA support removal is time‑consuming and risks scratching the surface. For the internal channel in this case, supports cannot even be reached, making the part scrap. SLS powder removal takes only 10-15 minutes and does not damage the part. SLA’s “low cost” often ignores the risk of support failure and the labor involved.

5.4 Batch Effect – SLS Advantage at Higher Volumes

When batch sizes exceed 500 parts, SLS can use dense nesting (3D stacking) to significantly reduce machine time cost, while SLA is limited by platform area and cannot stack. At that point, SLS per‑part cost may approach or even fall below SLA. Additionally, powder recycling efficiency improves, lowering material cost.

Chapter 6: How to Choose the Better Process? – Decision Matrix

Based on the above analysis, we summarize the following selection guidelines:

Prefer SLA when

• Part geometry is simple, with no undercuts, deep cavities, or internal channels
• High transparency or smooth surface needed (appearance models, transparent covers)
• Small batch (≤50 pieces) and low mechanical demands
• Cost‑sensitive and SLA supports can be easily removed
• No need for heat resistance, impact resistance, or fatigue resistance

Prefer SLS when

• Part has undercuts, internal channels, spiral structures, living hinges (SLS is the only option)
• Requires nylon’s toughness, fatigue resistance, impact resistance, heat resistance (80-100°C)
• Larger batch (>100 pieces) and cost‑sensitive – SLS stacking advantage becomes significant
• Part will be used long‑term or endure cyclic loading
• Matte surface finish is acceptable (or even preferred for anti‑slip texture)

Chapter 7: Real‑World Case – The Irreplaceability of SLS

A drone company needed 50 housings with internal air channels and snap‑fit features. They first tried SLA – supports could not be removed, all 10 samples were scrapped, losing over ¥5,000 in material and labor. They switched to SLS: although the per‑part cost was ¥117 (38% higher than SLA’s ¥85), they successfully delivered 50 qualified parts, and the snap‑fits survived 5,000 open‑close cycles without fracture. The customer concluded: “The extra ¥32 per part was the price for ‘being able to make it’ and ‘lasting’. Without that, even a cheaper SLA would have been wasted money.”

Conclusion: Cost Is Not the Only Criterion – Feasibility Comes First

SLA and SLS each have their strengths. SLA wins on cost and surface quality; SLS is irreplaceable in geometric freedom and material properties. When choosing a process, ask yourself three questions: 1. Can SLA actually make this shape? (Can supports be removed?) 2. Does the service environment require nylon’s performance? 3. What is the batch size and total cost? our provides a free process comparison analysis. We will evaluate your 3D model and objectively recommend SLA or SLS, with quotes for both. Upload your model and let us help you find the solution that is “feasible” and “cost‑optimal”.

👇 Call to Action: Upload Your Model – Get SLA vs. SLS Optimal Solution

Whether you need high‑precision appearance parts, complex internal‑cavity functional parts, or low‑volume production – our 3D printing service provides dual quotes for SLA and SLS plus feasibility analysis, helping you make the right decision.

Our promise: Free process feasibility assessment, response within 2 hours, transparent cost breakdown, no hidden fees.

Or just say: “I have a part – please compare SLA and SLS feasibility and cost.”
Barry will connect you with an applications engineer.

📊 Feasibility First, Then Cost 📊

P.S. First‑time customers who upload a model through our website receive a free “SLA vs SLS Feasibility Analysis Report”. Mention “process comparison” when inquiring.

Barry Zeng
Senior Applications Engineer, Shanghai Yunyan Prototype & Mould Manufacture Factory
(An engineer who insists: “We talk price only after we confirm it can be made.”)

Keywords: 3D printing, SLA, SLS, stereolithography, selective laser sintering, cost comparison, low‑volume production, rapid prototyping, nylon printing, resin printing, material cost, machine time, post‑processing, support structures, powder recycling, drone housing, functional prototype, appearance model, batch effect, equipment depreciation, labor cost, process selection, decision matrix, DFM analysis, quoting comparison, transparent cost, photopolymer resin, nylon PA12, part height, support removal, blasting, internal channels, undercuts, living hinges, snap‑fit testing, total cost of ownership