Mechanical Design Fundamentals – Types of Stress

 🔧 Mechanical Design Fundamentals – Types of Stress

In mechanical design, every component experiences forces. How these forces act determines the type of stress inside the material. A good designer must understand these before creating CAD/CAE models.

1️⃣ Stress (σ)

📌 Definition → Internal resistance offered by a material per unit area when an external force is applied.

📌 Formula → σ = F / A

📌 Units → N/m² (Pascal or MPa)

✔ Why it matters? Stress analysis ensures that parts don’t fail under real-world loads.

2️⃣ Tensile Stress (Tension)

Occurs when forces try to stretch or pull apart a material.

👉 Example → A rope in a crane lifting a load, or a bolt under axial pulling force.

✔ Designers must ensure the ultimate tensile strength (UTS) of the material is higher than working stress.

3️⃣ Compressive Stress (Compression)

When forces push or squeeze a material, reducing its length.

👉 Example → Columns, pistons, or press-fit joints.

⚠ Risk → Buckling (sudden sideways failure in long slender members).

4️⃣ Shear Stress (τ)

When forces act parallel to the surface, causing layers to slide over each other.

📌 Formula → τ = F / A (parallel force / shear area)

👉 Example → Rivets, bolts under shear, scissors cutting paper.

✔ Important in fastener and joint design.

5️⃣ Torsional Stress (Twisting)

When torque (rotational force) is applied, causing shear stress around the axis.

👉 Example → Shafts in engines, gearboxes, propellers.

📌 Formula → τ = T·r / J

T = Torque

r = Radius

J = Polar moment of inertia

✔ Key design factor → Angle of twist must be within limits to avoid misalignment.

6️⃣ Bending Stress (Flexural)

When a beam or shaft is subjected to a load that causes it to bend.

👉 Combination of tension (at one side) and compression (at the other).

📌 Formula → σ = M·y / I

M = Bending moment

y = Distance from neutral axis

I = Moment of inertia

👉 Example → Bridges, cantilever beams, levers.

✅ Why This Matters in CAD/CAE?

Every CAD design will eventually be checked in CAE. Knowing these stress types allows engineers to:

Select the right material

Apply the correct load conditions in FEA

Ensure safety & reliability of designs

source : Technocraft Academy

Manufacturing Efficiency is More Than Numbers…It’s Transformational Science that Delivers Value.

In my experience of deploying continuous process improvement, I’ve seen one truth repeat itself: small changes in cycle time create massive changes in organizational success.

Consider a real-world example from a Fortune 500 distribution center.

The facility struggled with a 12-hour lead time from order receipt to shipping. When we applied Manufacturing Cycle Time (MCT) and Manufacturing Cycle Efficiency (MCE) analysis, the data revealed that only 35 percent of production time was true value-added work.

The rest was waiting, unnecessary movement, or inefficient scheduling.

Through Lean tools like value stream mapping, Kaizen events, and standard work design, we cut average lead time from 12 hours to 8 hours.

That 4-hour reduction meant faster customer fulfillment, increased throughput capacity, and a remarkable financial impact, more than 3.2 million dollars in annualized savings through reduced overtime, lower inventory holding costs, and fewer expedited shipments.

The return on investment went far beyond financials. Employees who once felt pressured by bottlenecks were now empowered to work in a smoother, more predictable system. Morale increased as they could focus on craftsmanship and problem-solving rather than firefighting.

When people feel their contributions directly improve performance, you build a culture of ownership and innovation.

I have led these transformations across industries, from aerospace to government services and the outcomes are consistent.

The combination of measuring cycle efficiency and acting on it with Lean methods delivers scalable success. Organizations gain profitability, employees gain pride, and customers gain trust.

Continuous improvement is not just about efficiency metrics. It is about unlocking hidden capacity, protecting margins, and most importantly, enabling people to thrive in environments designed for excellence.

That is the real power of Lean.🔋

source : Shawn W

100% recycled material – 100% quality: New 3-layer PVC pipe head from KraussMaffei Extrusion

Sustainability is not just skin deep – it often begins underground: in our cities' pipe systems. This also applies to the production of PVC sewage pipes. At K 2025 in Düsseldorf (October 8–15), KraussMaffei Extrusion will present a new 3-layer pipe head that allows the safe and stable processing of up to 100% recycled material.

The company is thus sending a clear signal for greater resource conservation in pipe manufacturing while also meeting the growing demands of the circular economy.

New patent-pending flow system

Reliable processing of up to 100% recycled material in all three layers

Significant savings in material costs

Sustainable response to the growing market for PVC sewage pipes

Two years of development for a new standard:

The KM-3L RK 42-HP is the result of a completely new development – not a further development of existing concepts, but a pipe head that has been redesigned and simulated from scratch. With a processing range of 400 to 1,200 kg/h and a diameter of 110 to 250 mm, it is ideally suited for large-scale industrial applications. "With the new KM-3L RK 42-HP, we are presenting the most advanced 3-layer pipe head for PVC applications. Our customers benefit from economical, sustainable, and outstanding quality pipe production," says Ralf Benack, CEO KraussMaffei Extrusion.

 

Intelligent design for maximum performance:

At the heart of the new die head is a high-precision, patent-pending flow system with symmetrical material feed for all three layers. The solution for the core layer is particularly innovative. It benefits from a highly efficient 1-to-8 distribution, which enables extremely short dwell times and thus significantly reduces the susceptibility to errors. This allows 100 percent recycled material to be processed reliably, regardless of whether the layer is foamed or compact, and regardless of whether in-house recycled material or post-consumer waste is used.

The two cover layers are also characterized by maximum efficiency and flexibility. Currently, virgin material is predominantly used here, but the design is also suitable for the use of 100 percent recycled material.

Efficient and sustainable: The new 3-layer PVC pipe head from KraussMaffei Extrusion enables the safe and stable processing of up to 100% recycled material, even with highly variable material quality.

Stable processes, big savings

The new KM-3L RK 42-HP enables manufacturers to produce much more economically. "Thanks to the largest process window on the market, long production runs with minimal downtime are possible. At the same time, material costs are significantly reduced," says Dr. Thomas Unger, Vice President Technologies at KraussMaffei Extrusion. And since material typically accounts for the largest share of operating costs, even small savings have an immediate and noticeable effect on the overall calculation.

source : KraussMaffei

Today's KNOWLEDGE Share : Why Design & Simulation Matter in Extrusion Systems

Today's KNOWLEDGE Share

Why Design & Simulation Matter in Extrusion Systems

In extrusion technology – whether die heads, extruders, blown film, cast film, or MDO units – the quality of design defines the performance of the entire system.

A well-engineered design supported by advanced simulation tools (flow analysis, thermal, and structural simulations)ensures:

✔️ Uniform melt distribution inside die heads → consistent film thickness

✔️ Optimized screw geometry → higher throughput with lower energy consumption

✔️ Controlled cooling and stretching → improved film properties in MDO and cast film lines

✔️ Reduced trial-and-error → saving cost and accelerating time to market

Design without simulation is guesswork.

Simulation without deep process knowledge is incomplete.

🔑 Combining both is what leads to efficient, reliable, and sustainable extrusion systems.

Innovation in extrusion design is not about adding complexity – it’s about applying engineering intelligence + simulation accuracy to achieve better performance with fewer resources.

source : Shady Aboali

OQ and Milliken Collaborate to Bring New Injection Molding Grade to Market

OQ, an energy investment and development company, and diversified global manufacturer #Milliken & Company today announced the introduction of a new clarified random copolymer for injection molding applications.

OQ utilized Milliken’s #Millad®NX®8000 ECO additive solution to debut its Luban RP2251T #injectionmoldinggrade that has a superior aesthetic appearance and can be processed at significantly lower temperatures, enabling converters to generate #energysavings and improved #productivity due to reduced cycle times.

This innovation enables converters to reduce energy consumption and achieve higher productivity, directly contributing to sustainable manufacturing and #packaging solutions that meet evolving global needs.

“From product development to full commercialization, we are proud to collaborate with #OQ to introduce their first injection molding grade made with our Millad clarifying agent,” said Maria Di Nolfo, Europe Sales Director at Milliken. “We are eager to see OQ meet the growing demand for highly transparent reusable products with lower energy consumption.

#LubanRP2251T offers excellent transparency and organoleptic performance. The grade is typically used in the production of #thinwalledpackaging with high transparency and stringent requirements for #organoleptic properties.

“At OQ, we’re driven by innovation that delivers real-world performance, sustainability benefits and solutions for global megatrends. Luban RP2251T is a great example of how OQ and Milliken are advancing polymer performance, combining excellent clarity with lower energy use and faster cycle times,” said Abdulrahman Al Tamtami, VP Global Marketing at OQ.

OQ’s Luban RP2251T is enhanced with Millad clarifying agent, which provides excellent aesthetics and processing efficiency, enabling converters to achieve up to 10% energy and cost savings by processing the grades at lower temperatures and with shorter cycle times than similar products in the market, which use different clarifying agents.

source :Milliken

Today's KNOWLEDGE Share : Removing yellow stains from fabric with blue light

Today's KNOWLEDGE Share

Removing yellow stains from fabric with blue light

Sweat and food stains can ruin your favorite clothes. But bleaching agents such as hydrogen peroxide or dry-cleaning solvents that remove stains aren’t options for all fabrics, especially delicate ones. Now, researchers in ACS Sustainable Chemistry & Engineering report a simple way to remove yellow stains using a high-intensity blue LED light. They demonstrate the method’s effectiveness at removing stains from orange juice, tomato juice and sweat-like substances on multiple fabrics, including silk.

Our method utilizes visible blue light in combination with ambient oxygen, which acts as the oxidizing agent to drive the photobleaching process,” says Tomohiro Sugahara, the study’s corresponding author. “This approach avoids the use of harsh chemical oxidants typically required in conventional bleaching methods, making it inherently more sustainable.

Yellow clothing stains are caused by squalene and oleic acid from skin oils and sweat, as well as natural pigments like beta carotene and lycopene, present in oranges, tomatoes and other foods. UV light is a potential stain-removing alternative to chemical oxidizers like bleach and hydrogen peroxide, but it can damage delicate fabrics. Sugahara and Hisanari Yoneda previously determined that a high-intensity blue LED light could remove yellow color from aged resin polymers, and they wanted to see whether blue light could also break down yellow stains on fabric without causing damage.

Initially, they exposed vials of beta-carotene, lycopene and squalene to high-intensity blue LED light for three hours. All the samples lost color, and spectroscopic analyses indicated that oxygen in the air helped the photobleaching process by breaking bonds to produce colorless compounds. Next, the team applied squalene onto cotton fabric swatches.

After heating the swatches to simulate aging, they treated the samples for 10 minutes, by soaking them in a hydrogen peroxide solution or exposing them to the blue LED or UV light. The blue light reduced the yellow stain substantially more than the hydrogen peroxide or UV exposure. In fact, UV exposure generated some new yellow-colored compounds. Additional tests showed that the blue LED treatment lightened squalene stains on silk and polyester without damaging the fabrics. The method also reduced the color of other stain-causing substances, including aged oleic acid, orange juice and tomato juice, on cotton swatches.

High-intensity blue LED light is a promising way to remove clothing stains, but the researchers say they want to do additional colorfastness and safety testing before commercializing a light system for home and industrial use.

The authors do not have an external funding source for this work. They are employed by Asahi Kasei Corporation, a company that develops fiber products, chemicals and electronic materials.

source : The American Chemical Society (ACS)