𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞 : 𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝𝐢𝐧𝐠 𝐒𝐢𝐧𝐤 𝐌𝐚𝐫𝐤𝐬 𝐢𝐧 𝐈𝐧𝐣𝐞𝐜𝐭𝐢𝐨𝐧 𝐌𝐨𝐥𝐝𝐢𝐧𝐠 — 𝐌𝐨𝐫𝐞 𝐓𝐡𝐚𝐧 𝐉𝐮𝐬𝐭 𝐚 𝐒𝐮𝐫𝐟𝐚𝐜𝐞 𝐈𝐬𝐬𝐮𝐞

 𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞

🔹 𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝𝐢𝐧𝐠 𝐒𝐢𝐧𝐤 𝐌𝐚𝐫𝐤𝐬 𝐢𝐧 𝐈𝐧𝐣𝐞𝐜𝐭𝐢𝐨𝐧 𝐌𝐨𝐥𝐝𝐢𝐧𝐠 — 𝐌𝐨𝐫𝐞 𝐓𝐡𝐚𝐧 𝐉𝐮𝐬𝐭 𝐚 𝐒𝐮𝐫𝐟𝐚𝐜𝐞 𝐈𝐬𝐬𝐮𝐞

Sink marks are one of the most common defects in plastic parts — especially in thick or rib-supported areas.

They may look like small dents or depressions, but they reveal important information about how the part was filled and cooled.

🔍 Why do sink marks occur?

Sink marks typically form when:

🧊 Local cooling is slower in thick sections

🌀 Insufficient packing pressure during injection

🧱 Ribs or bosses are too thick

🧩 Material shrinks unevenly during solidification

Even a 0.5 mm geometry difference can create visible sinks — especially on glossy surfaces.

💡 𝐇𝐨𝐰 𝐭𝐨 𝐩𝐫𝐞𝐯𝐞𝐧𝐭 𝐬𝐢𝐧𝐤 𝐦𝐚𝐫𝐤𝐬

𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐬 𝐜𝐚𝐧 𝐫𝐞𝐝𝐮𝐜𝐞 𝐬𝐢𝐧𝐤 𝐦𝐚𝐫𝐤𝐬 𝐛𝐲:

📐 𝐃𝐞𝐬𝐢𝐠𝐧𝐢𝐧𝐠 𝐫𝐢𝐛𝐬 𝐚𝐭 𝟒𝟎–𝟔𝟎% 𝐨𝐟 𝐰𝐚𝐥𝐥 𝐭𝐡𝐢𝐜𝐤𝐧𝐞𝐬𝐬

🌡️ 𝐈𝐦𝐩𝐫𝐨𝐯𝐢𝐧𝐠 𝐜𝐨𝐨𝐥𝐢𝐧𝐠 𝐜𝐡𝐚𝐧𝐧𝐞𝐥 𝐥𝐚𝐲𝐨𝐮𝐭 𝐢𝐧 𝐭𝐡𝐞 𝐦𝐨𝐥𝐝

💨 𝐈𝐧𝐜𝐫𝐞𝐚𝐬𝐢𝐧𝐠 𝐩𝐚𝐜𝐤𝐢𝐧𝐠 𝐩𝐫𝐞𝐬𝐬𝐮𝐫𝐞 & 𝐡𝐨𝐥𝐝𝐢𝐧𝐠 𝐭𝐢𝐦𝐞

🧪 𝐔𝐬𝐢𝐧𝐠 𝐦𝐚𝐭𝐞𝐫𝐢𝐚𝐥𝐬 𝐰𝐢𝐭𝐡 𝐥𝐨𝐰𝐞𝐫 𝐬𝐡𝐫𝐢𝐧𝐤𝐚𝐠𝐞 𝐛𝐞𝐡𝐚𝐯𝐢𝐨𝐫 (𝐞.𝐠., 𝐏𝐂, 𝐀𝐁𝐒)

Proper geometry + balanced process settings = minimal sink marks.

🧠 Why this matters

Sink marks don’t always affect function —

but they will affect appearance, customer perception, and often assembly fit.

This is why SCSplastic evaluates ribbing, wall thickness, and cooling strategy already during the DFM phase.

Better design upfront = fewer defects later.

source : SCSplastic