For npm to work behind corporate web proxy, 3 configuration command is needed. Make sure, you have them all.

    npm config set registry http://registry.npmjs.org/
    npm config set proxy http://proxy.company.com:8080
    npm config set https-proxy http://proxy.company.com:8080

Similarly, bower callso provide proxy configuration, edit .bowerrc file

    {
        "proxy": "http://proxy.company.com:8080/",
        "https-proxy": "http://proxy.company.com:8080/"
    }